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linux/drivers/i2c/busses/i2c-rk3x.c
Wolfram Sang b340db7351 i2c: rk3x: reword according to newest specification 
Change the wording of this driver wrt. the newest I2C v7 and SMBus 3.2
specifications and replace "master/slave" with more appropriate terms.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
2024-07-11 15:14:19 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for I2C adapter in Rockchip RK3xxx SoC
*
* Max Schwarz <max.schwarz@online.de>
* based on the patches by Rockchip Inc.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/spinlock.h>
#include <linux/clk.h>
#include <linux/wait.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
#include <linux/math64.h>
/* Register Map */
#define REG_CON 0x00 /* control register */
#define REG_CLKDIV 0x04 /* clock divisor register */
#define REG_MRXADDR 0x08 /* target address for REGISTER_TX */
#define REG_MRXRADDR 0x0c /* target register address for REGISTER_TX */
#define REG_MTXCNT 0x10 /* number of bytes to be transmitted */
#define REG_MRXCNT 0x14 /* number of bytes to be received */
#define REG_IEN 0x18 /* interrupt enable */
#define REG_IPD 0x1c /* interrupt pending */
#define REG_FCNT 0x20 /* finished count */
/* Data buffer offsets */
#define TXBUFFER_BASE 0x100
#define RXBUFFER_BASE 0x200
/* REG_CON bits */
#define REG_CON_EN BIT(0)
enum {
REG_CON_MOD_TX = 0, /* transmit data */
REG_CON_MOD_REGISTER_TX, /* select register and restart */
REG_CON_MOD_RX, /* receive data */
REG_CON_MOD_REGISTER_RX, /* broken: transmits read addr AND writes
* register addr */
};
#define REG_CON_MOD(mod) ((mod) << 1)
#define REG_CON_MOD_MASK (BIT(1) | BIT(2))
#define REG_CON_START BIT(3)
#define REG_CON_STOP BIT(4)
#define REG_CON_LASTACK BIT(5) /* 1: send NACK after last received byte */
#define REG_CON_ACTACK BIT(6) /* 1: stop if NACK is received */
#define REG_CON_TUNING_MASK GENMASK_ULL(15, 8)
#define REG_CON_SDA_CFG(cfg) ((cfg) << 8)
#define REG_CON_STA_CFG(cfg) ((cfg) << 12)
#define REG_CON_STO_CFG(cfg) ((cfg) << 14)
/* REG_MRXADDR bits */
#define REG_MRXADDR_VALID(x) BIT(24 + (x)) /* [x*8+7:x*8] of MRX[R]ADDR valid */
/* REG_IEN/REG_IPD bits */
#define REG_INT_BTF BIT(0) /* a byte was transmitted */
#define REG_INT_BRF BIT(1) /* a byte was received */
#define REG_INT_MBTF BIT(2) /* controller data transmit finished */
#define REG_INT_MBRF BIT(3) /* controller data receive finished */
#define REG_INT_START BIT(4) /* START condition generated */
#define REG_INT_STOP BIT(5) /* STOP condition generated */
#define REG_INT_NAKRCV BIT(6) /* NACK received */
#define REG_INT_ALL 0x7f
/* Constants */
#define WAIT_TIMEOUT 1000 /* ms */
#define DEFAULT_SCL_RATE (100 * 1000) /* Hz */
/**
* struct i2c_spec_values - I2C specification values for various modes
* @min_hold_start_ns: min hold time (repeated) START condition
* @min_low_ns: min LOW period of the SCL clock
* @min_high_ns: min HIGH period of the SCL cloc
* @min_setup_start_ns: min set-up time for a repeated START conditio
* @max_data_hold_ns: max data hold time
* @min_data_setup_ns: min data set-up time
* @min_setup_stop_ns: min set-up time for STOP condition
* @min_hold_buffer_ns: min bus free time between a STOP and
* START condition
*/
struct i2c_spec_values {
unsigned long min_hold_start_ns;
unsigned long min_low_ns;
unsigned long min_high_ns;
unsigned long min_setup_start_ns;
unsigned long max_data_hold_ns;
unsigned long min_data_setup_ns;
unsigned long min_setup_stop_ns;
unsigned long min_hold_buffer_ns;
};
static const struct i2c_spec_values standard_mode_spec = {
.min_hold_start_ns = 4000,
.min_low_ns = 4700,
.min_high_ns = 4000,
.min_setup_start_ns = 4700,
.max_data_hold_ns = 3450,
.min_data_setup_ns = 250,
.min_setup_stop_ns = 4000,
.min_hold_buffer_ns = 4700,
};
static const struct i2c_spec_values fast_mode_spec = {
.min_hold_start_ns = 600,
.min_low_ns = 1300,
.min_high_ns = 600,
.min_setup_start_ns = 600,
.max_data_hold_ns = 900,
.min_data_setup_ns = 100,
.min_setup_stop_ns = 600,
.min_hold_buffer_ns = 1300,
};
static const struct i2c_spec_values fast_mode_plus_spec = {
.min_hold_start_ns = 260,
.min_low_ns = 500,
.min_high_ns = 260,
.min_setup_start_ns = 260,
.max_data_hold_ns = 400,
.min_data_setup_ns = 50,
.min_setup_stop_ns = 260,
.min_hold_buffer_ns = 500,
};
/**
* struct rk3x_i2c_calced_timings - calculated V1 timings
* @div_low: Divider output for low
* @div_high: Divider output for high
* @tuning: Used to adjust setup/hold data time,
* setup/hold start time and setup stop time for
* v1's calc_timings, the tuning should all be 0
* for old hardware anyone using v0's calc_timings.
*/
struct rk3x_i2c_calced_timings {
unsigned long div_low;
unsigned long div_high;
unsigned int tuning;
};
enum rk3x_i2c_state {
STATE_IDLE,
STATE_START,
STATE_READ,
STATE_WRITE,
STATE_STOP
};
/**
* struct rk3x_i2c_soc_data - SOC-specific data
* @grf_offset: offset inside the grf regmap for setting the i2c type
* @calc_timings: Callback function for i2c timing information calculated
*/
struct rk3x_i2c_soc_data {
int grf_offset;
int (*calc_timings)(unsigned long, struct i2c_timings *,
struct rk3x_i2c_calced_timings *);
};
/**
* struct rk3x_i2c - private data of the controller
* @adap: corresponding I2C adapter
* @dev: device for this controller
* @soc_data: related soc data struct
* @regs: virtual memory area
* @clk: function clk for rk3399 or function & Bus clks for others
* @pclk: Bus clk for rk3399
* @clk_rate_nb: i2c clk rate change notify
* @irq: irq number
* @t: I2C known timing information
* @lock: spinlock for the i2c bus
* @wait: the waitqueue to wait for i2c transfer
* @busy: the condition for the event to wait for
* @msg: current i2c message
* @addr: addr of i2c target device
* @mode: mode of i2c transfer
* @is_last_msg: flag determines whether it is the last msg in this transfer
* @state: state of i2c transfer
* @processed: byte length which has been send or received
* @error: error code for i2c transfer
*/
struct rk3x_i2c {
struct i2c_adapter adap;
struct device *dev;
const struct rk3x_i2c_soc_data *soc_data;
/* Hardware resources */
void __iomem *regs;
struct clk *clk;
struct clk *pclk;
struct notifier_block clk_rate_nb;
int irq;
/* Settings */
struct i2c_timings t;
/* Synchronization & notification */
spinlock_t lock;
wait_queue_head_t wait;
bool busy;
/* Current message */
struct i2c_msg *msg;
u8 addr;
unsigned int mode;
bool is_last_msg;
/* I2C state machine */
enum rk3x_i2c_state state;
unsigned int processed;
int error;
};
static inline void i2c_writel(struct rk3x_i2c *i2c, u32 value,
unsigned int offset)
{
writel(value, i2c->regs + offset);
}
static inline u32 i2c_readl(struct rk3x_i2c *i2c, unsigned int offset)
{
return readl(i2c->regs + offset);
}
/* Reset all interrupt pending bits */
static inline void rk3x_i2c_clean_ipd(struct rk3x_i2c *i2c)
{
i2c_writel(i2c, REG_INT_ALL, REG_IPD);
}
/**
* rk3x_i2c_start - Generate a START condition, which triggers a REG_INT_START interrupt.
* @i2c: target controller data
*/
static void rk3x_i2c_start(struct rk3x_i2c *i2c)
{
u32 val = i2c_readl(i2c, REG_CON) & REG_CON_TUNING_MASK;
i2c_writel(i2c, REG_INT_START, REG_IEN);
/* enable adapter with correct mode, send START condition */
val |= REG_CON_EN | REG_CON_MOD(i2c->mode) | REG_CON_START;
/* if we want to react to NACK, set ACTACK bit */
if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
val |= REG_CON_ACTACK;
i2c_writel(i2c, val, REG_CON);
}
/**
* rk3x_i2c_stop - Generate a STOP condition, which triggers a REG_INT_STOP interrupt.
* @i2c: target controller data
* @error: Error code to return in rk3x_i2c_xfer
*/
static void rk3x_i2c_stop(struct rk3x_i2c *i2c, int error)
{
unsigned int ctrl;
i2c->processed = 0;
i2c->msg = NULL;
i2c->error = error;
if (i2c->is_last_msg) {
/* Enable stop interrupt */
i2c_writel(i2c, REG_INT_STOP, REG_IEN);
i2c->state = STATE_STOP;
ctrl = i2c_readl(i2c, REG_CON);
ctrl |= REG_CON_STOP;
i2c_writel(i2c, ctrl, REG_CON);
} else {
/* Signal rk3x_i2c_xfer to start the next message. */
i2c->busy = false;
i2c->state = STATE_IDLE;
/*
* The HW is actually not capable of REPEATED START. But we can
* get the intended effect by resetting its internal state
* and issuing an ordinary START.
*/
ctrl = i2c_readl(i2c, REG_CON) & REG_CON_TUNING_MASK;
i2c_writel(i2c, ctrl, REG_CON);
/* signal that we are finished with the current msg */
wake_up(&i2c->wait);
}
}
/**
* rk3x_i2c_prepare_read - Setup a read according to i2c->msg
* @i2c: target controller data
*/
static void rk3x_i2c_prepare_read(struct rk3x_i2c *i2c)
{
unsigned int len = i2c->msg->len - i2c->processed;
u32 con;
con = i2c_readl(i2c, REG_CON);
/*
* The hw can read up to 32 bytes at a time. If we need more than one
* chunk, send an ACK after the last byte of the current chunk.
*/
if (len > 32) {
len = 32;
con &= ~REG_CON_LASTACK;
} else {
con |= REG_CON_LASTACK;
}
/* make sure we are in plain RX mode if we read a second chunk */
if (i2c->processed != 0) {
con &= ~REG_CON_MOD_MASK;
con |= REG_CON_MOD(REG_CON_MOD_RX);
}
i2c_writel(i2c, con, REG_CON);
i2c_writel(i2c, len, REG_MRXCNT);
}
/**
* rk3x_i2c_fill_transmit_buf - Fill the transmit buffer with data from i2c->msg
* @i2c: target controller data
*/
static void rk3x_i2c_fill_transmit_buf(struct rk3x_i2c *i2c)
{
unsigned int i, j;
u32 cnt = 0;
u32 val;
u8 byte;
for (i = 0; i < 8; ++i) {
val = 0;
for (j = 0; j < 4; ++j) {
if ((i2c->processed == i2c->msg->len) && (cnt != 0))
break;
if (i2c->processed == 0 && cnt == 0)
byte = (i2c->addr & 0x7f) << 1;
else
byte = i2c->msg->buf[i2c->processed++];
val |= byte << (j * 8);
cnt++;
}
i2c_writel(i2c, val, TXBUFFER_BASE + 4 * i);
if (i2c->processed == i2c->msg->len)
break;
}
i2c_writel(i2c, cnt, REG_MTXCNT);
}
/* IRQ handlers for individual states */
static void rk3x_i2c_handle_start(struct rk3x_i2c *i2c, unsigned int ipd)
{
if (!(ipd & REG_INT_START)) {
rk3x_i2c_stop(i2c, -EIO);
dev_warn(i2c->dev, "unexpected irq in START: 0x%x\n", ipd);
rk3x_i2c_clean_ipd(i2c);
return;
}
/* ack interrupt */
i2c_writel(i2c, REG_INT_START, REG_IPD);
/* disable start bit */
i2c_writel(i2c, i2c_readl(i2c, REG_CON) & ~REG_CON_START, REG_CON);
/* enable appropriate interrupts and transition */
if (i2c->mode == REG_CON_MOD_TX) {
i2c_writel(i2c, REG_INT_MBTF | REG_INT_NAKRCV, REG_IEN);
i2c->state = STATE_WRITE;
rk3x_i2c_fill_transmit_buf(i2c);
} else {
/* in any other case, we are going to be reading. */
i2c_writel(i2c, REG_INT_MBRF | REG_INT_NAKRCV, REG_IEN);
i2c->state = STATE_READ;
rk3x_i2c_prepare_read(i2c);
}
}
static void rk3x_i2c_handle_write(struct rk3x_i2c *i2c, unsigned int ipd)
{
if (!(ipd & REG_INT_MBTF)) {
rk3x_i2c_stop(i2c, -EIO);
dev_err(i2c->dev, "unexpected irq in WRITE: 0x%x\n", ipd);
rk3x_i2c_clean_ipd(i2c);
return;
}
/* ack interrupt */
i2c_writel(i2c, REG_INT_MBTF, REG_IPD);
/* are we finished? */
if (i2c->processed == i2c->msg->len)
rk3x_i2c_stop(i2c, i2c->error);
else
rk3x_i2c_fill_transmit_buf(i2c);
}
static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd)
{
unsigned int i;
unsigned int len = i2c->msg->len - i2c->processed;
u32 val;
u8 byte;
/* we only care for MBRF here. */
if (!(ipd & REG_INT_MBRF))
return;
/* ack interrupt (read also produces a spurious START flag, clear it too) */
i2c_writel(i2c, REG_INT_MBRF | REG_INT_START, REG_IPD);
/* Can only handle a maximum of 32 bytes at a time */
if (len > 32)
len = 32;
/* read the data from receive buffer */
for (i = 0; i < len; ++i) {
if (i % 4 == 0)
val = i2c_readl(i2c, RXBUFFER_BASE + (i / 4) * 4);
byte = (val >> ((i % 4) * 8)) & 0xff;
i2c->msg->buf[i2c->processed++] = byte;
}
/* are we finished? */
if (i2c->processed == i2c->msg->len)
rk3x_i2c_stop(i2c, i2c->error);
else
rk3x_i2c_prepare_read(i2c);
}
static void rk3x_i2c_handle_stop(struct rk3x_i2c *i2c, unsigned int ipd)
{
unsigned int con;
if (!(ipd & REG_INT_STOP)) {
rk3x_i2c_stop(i2c, -EIO);
dev_err(i2c->dev, "unexpected irq in STOP: 0x%x\n", ipd);
rk3x_i2c_clean_ipd(i2c);
return;
}
/* ack interrupt */
i2c_writel(i2c, REG_INT_STOP, REG_IPD);
/* disable STOP bit */
con = i2c_readl(i2c, REG_CON);
con &= ~REG_CON_STOP;
i2c_writel(i2c, con, REG_CON);
i2c->busy = false;
i2c->state = STATE_IDLE;
/* signal rk3x_i2c_xfer that we are finished */
wake_up(&i2c->wait);
}
static irqreturn_t rk3x_i2c_irq(int irqno, void *dev_id)
{
struct rk3x_i2c *i2c = dev_id;
unsigned int ipd;
spin_lock(&i2c->lock);
ipd = i2c_readl(i2c, REG_IPD);
if (i2c->state == STATE_IDLE) {
dev_warn(i2c->dev, "irq in STATE_IDLE, ipd = 0x%x\n", ipd);
rk3x_i2c_clean_ipd(i2c);
goto out;
}
dev_dbg(i2c->dev, "IRQ: state %d, ipd: %x\n", i2c->state, ipd);
/* Clean interrupt bits we don't care about */
ipd &= ~(REG_INT_BRF | REG_INT_BTF);
if (ipd & REG_INT_NAKRCV) {
/*
* We got a NACK in the last operation. Depending on whether
* IGNORE_NAK is set, we have to stop the operation and report
* an error.
*/
i2c_writel(i2c, REG_INT_NAKRCV, REG_IPD);
ipd &= ~REG_INT_NAKRCV;
if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
rk3x_i2c_stop(i2c, -ENXIO);
}
/* is there anything left to handle? */
if ((ipd & REG_INT_ALL) == 0)
goto out;
switch (i2c->state) {
case STATE_START:
rk3x_i2c_handle_start(i2c, ipd);
break;
case STATE_WRITE:
rk3x_i2c_handle_write(i2c, ipd);
break;
case STATE_READ:
rk3x_i2c_handle_read(i2c, ipd);
break;
case STATE_STOP:
rk3x_i2c_handle_stop(i2c, ipd);
break;
case STATE_IDLE:
break;
}
out:
spin_unlock(&i2c->lock);
return IRQ_HANDLED;
}
/**
* rk3x_i2c_get_spec - Get timing values of I2C specification
* @speed: Desired SCL frequency
*
* Return: Matched i2c_spec_values.
*/
static const struct i2c_spec_values *rk3x_i2c_get_spec(unsigned int speed)
{
if (speed <= I2C_MAX_STANDARD_MODE_FREQ)
return &standard_mode_spec;
else if (speed <= I2C_MAX_FAST_MODE_FREQ)
return &fast_mode_spec;
else
return &fast_mode_plus_spec;
}
/**
* rk3x_i2c_v0_calc_timings - Calculate divider values for desired SCL frequency
* @clk_rate: I2C input clock rate
* @t: Known I2C timing information
* @t_calc: Caculated rk3x private timings that would be written into regs
*
* Return: %0 on success, -%EINVAL if the goal SCL rate is too slow. In that case
* a best-effort divider value is returned in divs. If the target rate is
* too high, we silently use the highest possible rate.
*/
static int rk3x_i2c_v0_calc_timings(unsigned long clk_rate,
struct i2c_timings *t,
struct rk3x_i2c_calced_timings *t_calc)
{
unsigned long min_low_ns, min_high_ns;
unsigned long max_low_ns, min_total_ns;
unsigned long clk_rate_khz, scl_rate_khz;
unsigned long min_low_div, min_high_div;
unsigned long max_low_div;
unsigned long min_div_for_hold, min_total_div;
unsigned long extra_div, extra_low_div, ideal_low_div;
unsigned long data_hold_buffer_ns = 50;
const struct i2c_spec_values *spec;
int ret = 0;
/* Only support standard-mode and fast-mode */
if (WARN_ON(t->bus_freq_hz > I2C_MAX_FAST_MODE_FREQ))
t->bus_freq_hz = I2C_MAX_FAST_MODE_FREQ;
/* prevent scl_rate_khz from becoming 0 */
if (WARN_ON(t->bus_freq_hz < 1000))
t->bus_freq_hz = 1000;
/*
* min_low_ns: The minimum number of ns we need to hold low to
* meet I2C specification, should include fall time.
* min_high_ns: The minimum number of ns we need to hold high to
* meet I2C specification, should include rise time.
* max_low_ns: The maximum number of ns we can hold low to meet
* I2C specification.
*
* Note: max_low_ns should be (maximum data hold time * 2 - buffer)
* This is because the i2c host on Rockchip holds the data line
* for half the low time.
*/
spec = rk3x_i2c_get_spec(t->bus_freq_hz);
min_high_ns = t->scl_rise_ns + spec->min_high_ns;
/*
* Timings for repeated start:
* - controller appears to drop SDA at .875x (7/8) programmed clk high.
* - controller appears to keep SCL high for 2x programmed clk high.
*
* We need to account for those rules in picking our "high" time so
* we meet tSU;STA and tHD;STA times.
*/
min_high_ns = max(min_high_ns, DIV_ROUND_UP(
(t->scl_rise_ns + spec->min_setup_start_ns) * 1000, 875));
min_high_ns = max(min_high_ns, DIV_ROUND_UP(
(t->scl_rise_ns + spec->min_setup_start_ns + t->sda_fall_ns +
spec->min_high_ns), 2));
min_low_ns = t->scl_fall_ns + spec->min_low_ns;
max_low_ns = spec->max_data_hold_ns * 2 - data_hold_buffer_ns;
min_total_ns = min_low_ns + min_high_ns;
/* Adjust to avoid overflow */
clk_rate_khz = DIV_ROUND_UP(clk_rate, 1000);
scl_rate_khz = t->bus_freq_hz / 1000;
/*
* We need the total div to be >= this number
* so we don't clock too fast.
*/
min_total_div = DIV_ROUND_UP(clk_rate_khz, scl_rate_khz * 8);
/* These are the min dividers needed for min hold times. */
min_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns, 8 * 1000000);
min_high_div = DIV_ROUND_UP(clk_rate_khz * min_high_ns, 8 * 1000000);
min_div_for_hold = (min_low_div + min_high_div);
/*
* This is the maximum divider so we don't go over the maximum.
* We don't round up here (we round down) since this is a maximum.
*/
max_low_div = clk_rate_khz * max_low_ns / (8 * 1000000);
if (min_low_div > max_low_div) {
WARN_ONCE(true,
"Conflicting, min_low_div %lu, max_low_div %lu\n",
min_low_div, max_low_div);
max_low_div = min_low_div;
}
if (min_div_for_hold > min_total_div) {
/*
* Time needed to meet hold requirements is important.
* Just use that.
*/
t_calc->div_low = min_low_div;
t_calc->div_high = min_high_div;
} else {
/*
* We've got to distribute some time among the low and high
* so we don't run too fast.
*/
extra_div = min_total_div - min_div_for_hold;
/*
* We'll try to split things up perfectly evenly,
* biasing slightly towards having a higher div
* for low (spend more time low).
*/
ideal_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns,
scl_rate_khz * 8 * min_total_ns);
/* Don't allow it to go over the maximum */
if (ideal_low_div > max_low_div)
ideal_low_div = max_low_div;
/*
* Handle when the ideal low div is going to take up
* more than we have.
*/
if (ideal_low_div > min_low_div + extra_div)
ideal_low_div = min_low_div + extra_div;
/* Give low the "ideal" and give high whatever extra is left */
extra_low_div = ideal_low_div - min_low_div;
t_calc->div_low = ideal_low_div;
t_calc->div_high = min_high_div + (extra_div - extra_low_div);
}
/*
* Adjust to the fact that the hardware has an implicit "+1".
* NOTE: Above calculations always produce div_low > 0 and div_high > 0.
*/
t_calc->div_low--;
t_calc->div_high--;
/* Give the tuning value 0, that would not update con register */
t_calc->tuning = 0;
/* Maximum divider supported by hw is 0xffff */
if (t_calc->div_low > 0xffff) {
t_calc->div_low = 0xffff;
ret = -EINVAL;
}
if (t_calc->div_high > 0xffff) {
t_calc->div_high = 0xffff;
ret = -EINVAL;
}
return ret;
}
/**
* rk3x_i2c_v1_calc_timings - Calculate timing values for desired SCL frequency
* @clk_rate: I2C input clock rate
* @t: Known I2C timing information
* @t_calc: Caculated rk3x private timings that would be written into regs
*
* Return: %0 on success, -%EINVAL if the goal SCL rate is too slow. In that case
* a best-effort divider value is returned in divs. If the target rate is
* too high, we silently use the highest possible rate.
* The following formulas are v1's method to calculate timings.
*
* l = divl + 1;
* h = divh + 1;
* s = sda_update_config + 1;
* u = start_setup_config + 1;
* p = stop_setup_config + 1;
* T = Tclk_i2c;
*
* tHigh = 8 * h * T;
* tLow = 8 * l * T;
*
* tHD;sda = (l * s + 1) * T;
* tSU;sda = [(8 - s) * l + 1] * T;
* tI2C = 8 * (l + h) * T;
*
* tSU;sta = (8h * u + 1) * T;
* tHD;sta = [8h * (u + 1) - 1] * T;
* tSU;sto = (8h * p + 1) * T;
*/
static int rk3x_i2c_v1_calc_timings(unsigned long clk_rate,
struct i2c_timings *t,
struct rk3x_i2c_calced_timings *t_calc)
{
unsigned long min_low_ns, min_high_ns;
unsigned long min_setup_start_ns, min_setup_data_ns;
unsigned long min_setup_stop_ns, max_hold_data_ns;
unsigned long clk_rate_khz, scl_rate_khz;
unsigned long min_low_div, min_high_div;
unsigned long min_div_for_hold, min_total_div;
unsigned long extra_div, extra_low_div;
unsigned long sda_update_cfg, stp_sta_cfg, stp_sto_cfg;
const struct i2c_spec_values *spec;
int ret = 0;
/* Support standard-mode, fast-mode and fast-mode plus */
if (WARN_ON(t->bus_freq_hz > I2C_MAX_FAST_MODE_PLUS_FREQ))
t->bus_freq_hz = I2C_MAX_FAST_MODE_PLUS_FREQ;
/* prevent scl_rate_khz from becoming 0 */
if (WARN_ON(t->bus_freq_hz < 1000))
t->bus_freq_hz = 1000;
/*
* min_low_ns: The minimum number of ns we need to hold low to
* meet I2C specification, should include fall time.
* min_high_ns: The minimum number of ns we need to hold high to
* meet I2C specification, should include rise time.
*/
spec = rk3x_i2c_get_spec(t->bus_freq_hz);
/* calculate min-divh and min-divl */
clk_rate_khz = DIV_ROUND_UP(clk_rate, 1000);
scl_rate_khz = t->bus_freq_hz / 1000;
min_total_div = DIV_ROUND_UP(clk_rate_khz, scl_rate_khz * 8);
min_high_ns = t->scl_rise_ns + spec->min_high_ns;
min_high_div = DIV_ROUND_UP(clk_rate_khz * min_high_ns, 8 * 1000000);
min_low_ns = t->scl_fall_ns + spec->min_low_ns;
min_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns, 8 * 1000000);
/*
* Final divh and divl must be greater than 0, otherwise the
* hardware would not output the i2c clk.
*/
min_high_div = (min_high_div < 1) ? 2 : min_high_div;
min_low_div = (min_low_div < 1) ? 2 : min_low_div;
/* These are the min dividers needed for min hold times. */
min_div_for_hold = (min_low_div + min_high_div);
/*
* This is the maximum divider so we don't go over the maximum.
* We don't round up here (we round down) since this is a maximum.
*/
if (min_div_for_hold >= min_total_div) {
/*
* Time needed to meet hold requirements is important.
* Just use that.
*/
t_calc->div_low = min_low_div;
t_calc->div_high = min_high_div;
} else {
/*
* We've got to distribute some time among the low and high
* so we don't run too fast.
* We'll try to split things up by the scale of min_low_div and
* min_high_div, biasing slightly towards having a higher div
* for low (spend more time low).
*/
extra_div = min_total_div - min_div_for_hold;
extra_low_div = DIV_ROUND_UP(min_low_div * extra_div,
min_div_for_hold);
t_calc->div_low = min_low_div + extra_low_div;
t_calc->div_high = min_high_div + (extra_div - extra_low_div);
}
/*
* calculate sda data hold count by the rules, data_upd_st:3
* is a appropriate value to reduce calculated times.
*/
for (sda_update_cfg = 3; sda_update_cfg > 0; sda_update_cfg--) {
max_hold_data_ns = DIV_ROUND_UP((sda_update_cfg
* (t_calc->div_low) + 1)
* 1000000, clk_rate_khz);
min_setup_data_ns = DIV_ROUND_UP(((8 - sda_update_cfg)
* (t_calc->div_low) + 1)
* 1000000, clk_rate_khz);
if ((max_hold_data_ns < spec->max_data_hold_ns) &&
(min_setup_data_ns > spec->min_data_setup_ns))
break;
}
/* calculate setup start config */
min_setup_start_ns = t->scl_rise_ns + spec->min_setup_start_ns;
stp_sta_cfg = DIV_ROUND_UP(clk_rate_khz * min_setup_start_ns
- 1000000, 8 * 1000000 * (t_calc->div_high));
/* calculate setup stop config */
min_setup_stop_ns = t->scl_rise_ns + spec->min_setup_stop_ns;
stp_sto_cfg = DIV_ROUND_UP(clk_rate_khz * min_setup_stop_ns
- 1000000, 8 * 1000000 * (t_calc->div_high));
t_calc->tuning = REG_CON_SDA_CFG(--sda_update_cfg) |
REG_CON_STA_CFG(--stp_sta_cfg) |
REG_CON_STO_CFG(--stp_sto_cfg);
t_calc->div_low--;
t_calc->div_high--;
/* Maximum divider supported by hw is 0xffff */
if (t_calc->div_low > 0xffff) {
t_calc->div_low = 0xffff;
ret = -EINVAL;
}
if (t_calc->div_high > 0xffff) {
t_calc->div_high = 0xffff;
ret = -EINVAL;
}
return ret;
}
static void rk3x_i2c_adapt_div(struct rk3x_i2c *i2c, unsigned long clk_rate)
{
struct i2c_timings *t = &i2c->t;
struct rk3x_i2c_calced_timings calc;
u64 t_low_ns, t_high_ns;
unsigned long flags;
u32 val;
int ret;
ret = i2c->soc_data->calc_timings(clk_rate, t, &calc);
WARN_ONCE(ret != 0, "Could not reach SCL freq %u", t->bus_freq_hz);
clk_enable(i2c->pclk);
spin_lock_irqsave(&i2c->lock, flags);
val = i2c_readl(i2c, REG_CON);
val &= ~REG_CON_TUNING_MASK;
val |= calc.tuning;
i2c_writel(i2c, val, REG_CON);
i2c_writel(i2c, (calc.div_high << 16) | (calc.div_low & 0xffff),
REG_CLKDIV);
spin_unlock_irqrestore(&i2c->lock, flags);
clk_disable(i2c->pclk);
t_low_ns = div_u64(((u64)calc.div_low + 1) * 8 * 1000000000, clk_rate);
t_high_ns = div_u64(((u64)calc.div_high + 1) * 8 * 1000000000,
clk_rate);
dev_dbg(i2c->dev,
"CLK %lukhz, Req %uns, Act low %lluns high %lluns\n",
clk_rate / 1000,
1000000000 / t->bus_freq_hz,
t_low_ns, t_high_ns);
}
/**
* rk3x_i2c_clk_notifier_cb - Clock rate change callback
* @nb: Pointer to notifier block
* @event: Notification reason
* @data: Pointer to notification data object
*
* The callback checks whether a valid bus frequency can be generated after the
* change. If so, the change is acknowledged, otherwise the change is aborted.
* New dividers are written to the HW in the pre- or post change notification
* depending on the scaling direction.
*
* Code adapted from i2c-cadence.c.
*
* Return: NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK
* to acknowledge the change, NOTIFY_DONE if the notification is
* considered irrelevant.
*/
static int rk3x_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
event, void *data)
{
struct clk_notifier_data *ndata = data;
struct rk3x_i2c *i2c = container_of(nb, struct rk3x_i2c, clk_rate_nb);
struct rk3x_i2c_calced_timings calc;
switch (event) {
case PRE_RATE_CHANGE:
/*
* Try the calculation (but don't store the result) ahead of
* time to see if we need to block the clock change. Timings
* shouldn't actually take effect until rk3x_i2c_adapt_div().
*/
if (i2c->soc_data->calc_timings(ndata->new_rate, &i2c->t,
&calc) != 0)
return NOTIFY_STOP;
/* scale up */
if (ndata->new_rate > ndata->old_rate)
rk3x_i2c_adapt_div(i2c, ndata->new_rate);
return NOTIFY_OK;
case POST_RATE_CHANGE:
/* scale down */
if (ndata->new_rate < ndata->old_rate)
rk3x_i2c_adapt_div(i2c, ndata->new_rate);
return NOTIFY_OK;
case ABORT_RATE_CHANGE:
/* scale up */
if (ndata->new_rate > ndata->old_rate)
rk3x_i2c_adapt_div(i2c, ndata->old_rate);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
/**
* rk3x_i2c_setup - Setup I2C registers for an I2C operation specified by msgs, num.
* @i2c: target controller data
* @msgs: I2C msgs to process
* @num: Number of msgs
*
* Must be called with i2c->lock held.
*
* Return: Number of I2C msgs processed or negative in case of error
*/
static int rk3x_i2c_setup(struct rk3x_i2c *i2c, struct i2c_msg *msgs, int num)
{
u32 addr = (msgs[0].addr & 0x7f) << 1;
int ret = 0;
/*
* The I2C adapter can issue a small (len < 4) write packet before
* reading. This speeds up SMBus-style register reads.
* The MRXADDR/MRXRADDR hold the target address and the target register
* address in this case.
*/
if (num >= 2 && msgs[0].len < 4 &&
!(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD)) {
u32 reg_addr = 0;
int i;
dev_dbg(i2c->dev, "Combined write/read from addr 0x%x\n",
addr >> 1);
/* Fill MRXRADDR with the register address(es) */
for (i = 0; i < msgs[0].len; ++i) {
reg_addr |= msgs[0].buf[i] << (i * 8);
reg_addr |= REG_MRXADDR_VALID(i);
}
/* msgs[0] is handled by hw. */
i2c->msg = &msgs[1];
i2c->mode = REG_CON_MOD_REGISTER_TX;
i2c_writel(i2c, addr | REG_MRXADDR_VALID(0), REG_MRXADDR);
i2c_writel(i2c, reg_addr, REG_MRXRADDR);
ret = 2;
} else {
/*
* We'll have to do it the boring way and process the msgs
* one-by-one.
*/
if (msgs[0].flags & I2C_M_RD) {
addr |= 1; /* set read bit */
/*
* We have to transmit the target addr first. Use
* MOD_REGISTER_TX for that purpose.
*/
i2c->mode = REG_CON_MOD_REGISTER_TX;
i2c_writel(i2c, addr | REG_MRXADDR_VALID(0),
REG_MRXADDR);
i2c_writel(i2c, 0, REG_MRXRADDR);
} else {
i2c->mode = REG_CON_MOD_TX;
}
i2c->msg = &msgs[0];
ret = 1;
}
i2c->addr = msgs[0].addr;
i2c->busy = true;
i2c->state = STATE_START;
i2c->processed = 0;
i2c->error = 0;
rk3x_i2c_clean_ipd(i2c);
return ret;
}
static int rk3x_i2c_wait_xfer_poll(struct rk3x_i2c *i2c)
{
ktime_t timeout = ktime_add_ms(ktime_get(), WAIT_TIMEOUT);
while (READ_ONCE(i2c->busy) &&
ktime_compare(ktime_get(), timeout) < 0) {
udelay(5);
rk3x_i2c_irq(0, i2c);
}
return !i2c->busy;
}
static int rk3x_i2c_xfer_common(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num, bool polling)
{
struct rk3x_i2c *i2c = (struct rk3x_i2c *)adap->algo_data;
unsigned long flags;
long time_left;
u32 val;
int ret = 0;
int i;
spin_lock_irqsave(&i2c->lock, flags);
clk_enable(i2c->clk);
clk_enable(i2c->pclk);
i2c->is_last_msg = false;
/*
* Process msgs. We can handle more than one message at once (see
* rk3x_i2c_setup()).
*/
for (i = 0; i < num; i += ret) {
ret = rk3x_i2c_setup(i2c, msgs + i, num - i);
if (ret < 0) {
dev_err(i2c->dev, "rk3x_i2c_setup() failed\n");
break;
}
if (i + ret >= num)
i2c->is_last_msg = true;
spin_unlock_irqrestore(&i2c->lock, flags);
if (!polling) {
rk3x_i2c_start(i2c);
time_left = wait_event_timeout(i2c->wait, !i2c->busy,
msecs_to_jiffies(WAIT_TIMEOUT));
} else {
disable_irq(i2c->irq);
rk3x_i2c_start(i2c);
time_left = rk3x_i2c_wait_xfer_poll(i2c);
enable_irq(i2c->irq);
}
spin_lock_irqsave(&i2c->lock, flags);
if (time_left == 0) {
/* Force a STOP condition without interrupt */
i2c_writel(i2c, 0, REG_IEN);
val = i2c_readl(i2c, REG_CON) & REG_CON_TUNING_MASK;
val |= REG_CON_EN | REG_CON_STOP;
i2c_writel(i2c, val, REG_CON);
i2c->state = STATE_IDLE;
ret = -ETIMEDOUT;
break;
}
if (i2c->error) {
ret = i2c->error;
break;
}
}
clk_disable(i2c->pclk);
clk_disable(i2c->clk);
spin_unlock_irqrestore(&i2c->lock, flags);
return ret < 0 ? ret : num;
}
static int rk3x_i2c_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
return rk3x_i2c_xfer_common(adap, msgs, num, false);
}
static int rk3x_i2c_xfer_polling(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
return rk3x_i2c_xfer_common(adap, msgs, num, true);
}
static __maybe_unused int rk3x_i2c_resume(struct device *dev)
{
struct rk3x_i2c *i2c = dev_get_drvdata(dev);
rk3x_i2c_adapt_div(i2c, clk_get_rate(i2c->clk));
return 0;
}
static u32 rk3x_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
}
static const struct i2c_algorithm rk3x_i2c_algorithm = {
.xfer = rk3x_i2c_xfer,
.xfer_atomic = rk3x_i2c_xfer_polling,
.functionality = rk3x_i2c_func,
};
static const struct rk3x_i2c_soc_data rv1108_soc_data = {
.grf_offset = -1,
.calc_timings = rk3x_i2c_v1_calc_timings,
};
static const struct rk3x_i2c_soc_data rv1126_soc_data = {
.grf_offset = 0x118,
.calc_timings = rk3x_i2c_v1_calc_timings,
};
static const struct rk3x_i2c_soc_data rk3066_soc_data = {
.grf_offset = 0x154,
.calc_timings = rk3x_i2c_v0_calc_timings,
};
static const struct rk3x_i2c_soc_data rk3188_soc_data = {
.grf_offset = 0x0a4,
.calc_timings = rk3x_i2c_v0_calc_timings,
};
static const struct rk3x_i2c_soc_data rk3228_soc_data = {
.grf_offset = -1,
.calc_timings = rk3x_i2c_v0_calc_timings,
};
static const struct rk3x_i2c_soc_data rk3288_soc_data = {
.grf_offset = -1,
.calc_timings = rk3x_i2c_v0_calc_timings,
};
static const struct rk3x_i2c_soc_data rk3399_soc_data = {
.grf_offset = -1,
.calc_timings = rk3x_i2c_v1_calc_timings,
};
static const struct of_device_id rk3x_i2c_match[] = {
{
.compatible = "rockchip,rv1108-i2c",
.data = &rv1108_soc_data
},
{
.compatible = "rockchip,rv1126-i2c",
.data = &rv1126_soc_data
},
{
.compatible = "rockchip,rk3066-i2c",
.data = &rk3066_soc_data
},
{
.compatible = "rockchip,rk3188-i2c",
.data = &rk3188_soc_data
},
{
.compatible = "rockchip,rk3228-i2c",
.data = &rk3228_soc_data
},
{
.compatible = "rockchip,rk3288-i2c",
.data = &rk3288_soc_data
},
{
.compatible = "rockchip,rk3399-i2c",
.data = &rk3399_soc_data
},
{},
};
MODULE_DEVICE_TABLE(of, rk3x_i2c_match);
static int rk3x_i2c_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
const struct of_device_id *match;
struct rk3x_i2c *i2c;
int ret = 0;
int bus_nr;
u32 value;
int irq;
unsigned long clk_rate;
i2c = devm_kzalloc(&pdev->dev, sizeof(struct rk3x_i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
match = of_match_node(rk3x_i2c_match, np);
i2c->soc_data = match->data;
/* use common interface to get I2C timing properties */
i2c_parse_fw_timings(&pdev->dev, &i2c->t, true);
strscpy(i2c->adap.name, "rk3x-i2c", sizeof(i2c->adap.name));
i2c->adap.owner = THIS_MODULE;
i2c->adap.algo = &rk3x_i2c_algorithm;
i2c->adap.retries = 3;
i2c->adap.dev.of_node = np;
i2c->adap.algo_data = i2c;
i2c->adap.dev.parent = &pdev->dev;
i2c->dev = &pdev->dev;
spin_lock_init(&i2c->lock);
init_waitqueue_head(&i2c->wait);
i2c->regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(i2c->regs))
return PTR_ERR(i2c->regs);
/* Try to set the I2C adapter number from dt */
bus_nr = of_alias_get_id(np, "i2c");
/*
* Switch to new interface if the SoC also offers the old one.
* The control bit is located in the GRF register space.
*/
if (i2c->soc_data->grf_offset >= 0) {
struct regmap *grf;
grf = syscon_regmap_lookup_by_phandle(np, "rockchip,grf");
if (IS_ERR(grf)) {
dev_err(&pdev->dev,
"rk3x-i2c needs 'rockchip,grf' property\n");
return PTR_ERR(grf);
}
if (bus_nr < 0) {
dev_err(&pdev->dev, "rk3x-i2c needs i2cX alias");
return -EINVAL;
}
/* rv1126 i2c2 uses non-sequential write mask 20, value 4 */
if (i2c->soc_data == &rv1126_soc_data && bus_nr == 2)
value = BIT(20) | BIT(4);
else
/* 27+i: write mask, 11+i: value */
value = BIT(27 + bus_nr) | BIT(11 + bus_nr);
ret = regmap_write(grf, i2c->soc_data->grf_offset, value);
if (ret != 0) {
dev_err(i2c->dev, "Could not write to GRF: %d\n", ret);
return ret;
}
}
/* IRQ setup */
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
ret = devm_request_irq(&pdev->dev, irq, rk3x_i2c_irq,
0, dev_name(&pdev->dev), i2c);
if (ret < 0) {
dev_err(&pdev->dev, "cannot request IRQ\n");
return ret;
}
i2c->irq = irq;
platform_set_drvdata(pdev, i2c);
if (i2c->soc_data->calc_timings == rk3x_i2c_v0_calc_timings) {
/* Only one clock to use for bus clock and peripheral clock */
i2c->clk = devm_clk_get(&pdev->dev, NULL);
i2c->pclk = i2c->clk;
} else {
i2c->clk = devm_clk_get(&pdev->dev, "i2c");
i2c->pclk = devm_clk_get(&pdev->dev, "pclk");
}
if (IS_ERR(i2c->clk))
return dev_err_probe(&pdev->dev, PTR_ERR(i2c->clk),
"Can't get bus clk\n");
if (IS_ERR(i2c->pclk))
return dev_err_probe(&pdev->dev, PTR_ERR(i2c->pclk),
"Can't get periph clk\n");
ret = clk_prepare(i2c->clk);
if (ret < 0) {
dev_err(&pdev->dev, "Can't prepare bus clk: %d\n", ret);
return ret;
}
ret = clk_prepare(i2c->pclk);
if (ret < 0) {
dev_err(&pdev->dev, "Can't prepare periph clock: %d\n", ret);
goto err_clk;
}
i2c->clk_rate_nb.notifier_call = rk3x_i2c_clk_notifier_cb;
ret = clk_notifier_register(i2c->clk, &i2c->clk_rate_nb);
if (ret != 0) {
dev_err(&pdev->dev, "Unable to register clock notifier\n");
goto err_pclk;
}
ret = clk_enable(i2c->clk);
if (ret < 0) {
dev_err(&pdev->dev, "Can't enable bus clk: %d\n", ret);
goto err_clk_notifier;
}
clk_rate = clk_get_rate(i2c->clk);
rk3x_i2c_adapt_div(i2c, clk_rate);
clk_disable(i2c->clk);
ret = i2c_add_adapter(&i2c->adap);
if (ret < 0)
goto err_clk_notifier;
return 0;
err_clk_notifier:
clk_notifier_unregister(i2c->clk, &i2c->clk_rate_nb);
err_pclk:
clk_unprepare(i2c->pclk);
err_clk:
clk_unprepare(i2c->clk);
return ret;
}
static void rk3x_i2c_remove(struct platform_device *pdev)
{
struct rk3x_i2c *i2c = platform_get_drvdata(pdev);
i2c_del_adapter(&i2c->adap);
clk_notifier_unregister(i2c->clk, &i2c->clk_rate_nb);
clk_unprepare(i2c->pclk);
clk_unprepare(i2c->clk);
}
static SIMPLE_DEV_PM_OPS(rk3x_i2c_pm_ops, NULL, rk3x_i2c_resume);
static struct platform_driver rk3x_i2c_driver = {
.probe = rk3x_i2c_probe,
.remove_new = rk3x_i2c_remove,
.driver = {
.name = "rk3x-i2c",
.of_match_table = rk3x_i2c_match,
.pm = &rk3x_i2c_pm_ops,
},
};
module_platform_driver(rk3x_i2c_driver);
MODULE_DESCRIPTION("Rockchip RK3xxx I2C Bus driver");
MODULE_AUTHOR("Max Schwarz <max.schwarz@online.de>");
MODULE_LICENSE("GPL v2");
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