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linux/drivers/i2c/busses/i2c-rk3x.c

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/*
* Driver for I2C adapter in Rockchip RK3xxx SoC
*
* Max Schwarz <max.schwarz@online.de>
* based on the patches by Rockchip Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/interrupt.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>
/* Register Map */
#define REG_CON 0x00 /* control register */
#define REG_CLKDIV 0x04 /* clock divisor register */
#define REG_MRXADDR 0x08 /* slave address for REGISTER_TX */
#define REG_MRXRADDR 0x0c /* slave 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 */
/* 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) /* master data transmit finished */
#define REG_INT_MBRF BIT(3) /* master 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 200 /* ms */
#define DEFAULT_SCL_RATE (100 * 1000) /* Hz */
enum rk3x_i2c_state {
STATE_IDLE,
STATE_START,
STATE_READ,
STATE_WRITE,
STATE_STOP
};
/**
* @grf_offset: offset inside the grf regmap for setting the i2c type
*/
struct rk3x_i2c_soc_data {
int grf_offset;
};
struct rk3x_i2c {
struct i2c_adapter adap;
struct device *dev;
struct rk3x_i2c_soc_data *soc_data;
/* Hardware resources */
void __iomem *regs;
struct clk *clk;
/* Settings */
unsigned int scl_frequency;
/* 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; /* sent/received bytes */
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);
}
/**
* Generate a START condition, which triggers a REG_INT_START interrupt.
*/
static void rk3x_i2c_start(struct rk3x_i2c *i2c)
{
u32 val;
rk3x_i2c_clean_ipd(i2c);
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);
}
/**
* Generate a STOP condition, which triggers a REG_INT_STOP interrupt.
*
* @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.
*/
i2c_writel(i2c, 0, REG_CON);
/* signal that we are finished with the current msg */
wake_up(&i2c->wait);
}
}
/**
* Setup a read according to i2c->msg
*/
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 (unlikely(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);
}
/**
* Fill the transmit buffer with data from i2c->msg
*/
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)
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 uninitialized_var(val);
u8 byte;
/* we only care for MBRF here. */
if (!(ipd & REG_INT_MBRF))
return;
/* ack interrupt */
i2c_writel(i2c, REG_INT_MBRF, REG_IPD);
/* 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 (unlikely((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;
}
static void rk3x_i2c_set_scl_rate(struct rk3x_i2c *i2c, unsigned long scl_rate)
{
unsigned long i2c_rate = clk_get_rate(i2c->clk);
unsigned int div;
/* SCL rate = (clk rate) / (8 * DIV) */
div = DIV_ROUND_UP(i2c_rate, scl_rate * 8);
/* The lower and upper half of the CLKDIV reg describe the length of
* SCL low & high periods. */
div = DIV_ROUND_UP(div, 2);
i2c_writel(i2c, (div << 16) | (div & 0xffff), REG_CLKDIV);
}
/**
* Setup I2C registers for an I2C operation specified by msgs, num.
*
* Must be called with i2c->lock held.
*
* @msgs: I2C msgs to process
* @num: Number of msgs
*
* returns: 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 slave address and the slave 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 slave 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_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
struct rk3x_i2c *i2c = (struct rk3x_i2c *)adap->algo_data;
unsigned long timeout, flags;
int ret = 0;
int i;
spin_lock_irqsave(&i2c->lock, flags);
clk_enable(i2c->clk);
/* The clock rate might have changed, so setup the divider again */
rk3x_i2c_set_scl_rate(i2c, i2c->scl_frequency);
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);
rk3x_i2c_start(i2c);
timeout = wait_event_timeout(i2c->wait, !i2c->busy,
msecs_to_jiffies(WAIT_TIMEOUT));
spin_lock_irqsave(&i2c->lock, flags);
if (timeout == 0) {
dev_err(i2c->dev, "timeout, ipd: 0x%02x, state: %d\n",
i2c_readl(i2c, REG_IPD), i2c->state);
/* Force a STOP condition without interrupt */
i2c_writel(i2c, 0, REG_IEN);
i2c_writel(i2c, REG_CON_EN | REG_CON_STOP, REG_CON);
i2c->state = STATE_IDLE;
ret = -ETIMEDOUT;
break;
}
if (i2c->error) {
ret = i2c->error;
break;
}
}
clk_disable(i2c->clk);
spin_unlock_irqrestore(&i2c->lock, flags);
return ret;
}
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 = {
.master_xfer = rk3x_i2c_xfer,
.functionality = rk3x_i2c_func,
};
static struct rk3x_i2c_soc_data soc_data[3] = {
{ .grf_offset = 0x154 }, /* rk3066 */
{ .grf_offset = 0x0a4 }, /* rk3188 */
{ .grf_offset = -1 }, /* no I2C switching needed */
};
static const struct of_device_id rk3x_i2c_match[] = {
{ .compatible = "rockchip,rk3066-i2c", .data = (void *)&soc_data[0] },
{ .compatible = "rockchip,rk3188-i2c", .data = (void *)&soc_data[1] },
{ .compatible = "rockchip,rk3288-i2c", .data = (void *)&soc_data[2] },
{},
};
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;
struct resource *mem;
int ret = 0;
int bus_nr;
u32 value;
int irq;
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 = (struct rk3x_i2c_soc_data *)match->data;
if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
&i2c->scl_frequency)) {
dev_info(&pdev->dev, "using default SCL frequency: %d\n",
DEFAULT_SCL_RATE);
i2c->scl_frequency = DEFAULT_SCL_RATE;
}
if (i2c->scl_frequency == 0 || i2c->scl_frequency > 400 * 1000) {
dev_warn(&pdev->dev, "invalid SCL frequency specified.\n");
dev_warn(&pdev->dev, "using default SCL frequency: %d\n",
DEFAULT_SCL_RATE);
i2c->scl_frequency = DEFAULT_SCL_RATE;
}
strlcpy(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->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(i2c->clk)) {
dev_err(&pdev->dev, "cannot get clock\n");
return PTR_ERR(i2c->clk);
}
mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
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;
}
/* 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) {
dev_err(&pdev->dev, "cannot find rk3x IRQ\n");
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;
}
platform_set_drvdata(pdev, i2c);
ret = clk_prepare(i2c->clk);
if (ret < 0) {
dev_err(&pdev->dev, "Could not prepare clock\n");
return ret;
}
ret = i2c_add_adapter(&i2c->adap);
if (ret < 0) {
dev_err(&pdev->dev, "Could not register adapter\n");
goto err_clk;
}
dev_info(&pdev->dev, "Initialized RK3xxx I2C bus at %p\n", i2c->regs);
return 0;
err_clk:
clk_unprepare(i2c->clk);
return ret;
}
static int rk3x_i2c_remove(struct platform_device *pdev)
{
struct rk3x_i2c *i2c = platform_get_drvdata(pdev);
i2c_del_adapter(&i2c->adap);
clk_unprepare(i2c->clk);
return 0;
}
static struct platform_driver rk3x_i2c_driver = {
.probe = rk3x_i2c_probe,
.remove = rk3x_i2c_remove,
.driver = {
.owner = THIS_MODULE,
.name = "rk3x-i2c",
.of_match_table = rk3x_i2c_match,
},
};
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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