/*
* Copyright (C) 2007-2012 ST-Ericsson AB
* License terms: GNU General Public License (GPL) version 2
* ST DDC I2C master mode driver, used in e.g. U300 series platforms.
* Author: Linus Walleij <linus.walleij@stericsson.com>
* Author: Jonas Aaberg <jonas.aberg@stericsson.com>
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/of_i2c.h>
/* the name of this kernel module */
#define NAME "stu300"
/* CR (Control Register) 8bit (R/W) */
#define I2C_CR (0x00000000)
#define I2C_CR_RESET_VALUE (0x00)
#define I2C_CR_RESET_UMASK (0x00)
#define I2C_CR_DDC1_ENABLE (0x80)
#define I2C_CR_TRANS_ENABLE (0x40)
#define I2C_CR_PERIPHERAL_ENABLE (0x20)
#define I2C_CR_DDC2B_ENABLE (0x10)
#define I2C_CR_START_ENABLE (0x08)
#define I2C_CR_ACK_ENABLE (0x04)
#define I2C_CR_STOP_ENABLE (0x02)
#define I2C_CR_INTERRUPT_ENABLE (0x01)
/* SR1 (Status Register 1) 8bit (R/-) */
#define I2C_SR1 (0x00000004)
#define I2C_SR1_RESET_VALUE (0x00)
#define I2C_SR1_RESET_UMASK (0x00)
#define I2C_SR1_EVF_IND (0x80)
#define I2C_SR1_ADD10_IND (0x40)
#define I2C_SR1_TRA_IND (0x20)
#define I2C_SR1_BUSY_IND (0x10)
#define I2C_SR1_BTF_IND (0x08)
#define I2C_SR1_ADSL_IND (0x04)
#define I2C_SR1_MSL_IND (0x02)
#define I2C_SR1_SB_IND (0x01)
/* SR2 (Status Register 2) 8bit (R/-) */
#define I2C_SR2 (0x00000008)
#define I2C_SR2_RESET_VALUE (0x00)
#define I2C_SR2_RESET_UMASK (0x40)
#define I2C_SR2_MASK (0xBF)
#define I2C_SR2_SCLFAL_IND (0x80)
#define I2C_SR2_ENDAD_IND (0x20)
#define I2C_SR2_AF_IND (0x10)
#define I2C_SR2_STOPF_IND (0x08)
#define I2C_SR2_ARLO_IND (0x04)
#define I2C_SR2_BERR_IND (0x02)
#define I2C_SR2_DDC2BF_IND (0x01)
/* CCR (Clock Control Register) 8bit (R/W) */
#define I2C_CCR (0x0000000C)
#define I2C_CCR_RESET_VALUE (0x00)
#define I2C_CCR_RESET_UMASK (0x00)
#define I2C_CCR_MASK (0xFF)
#define I2C_CCR_FMSM (0x80)
#define I2C_CCR_CC_MASK (0x7F)
/* OAR1 (Own Address Register 1) 8bit (R/W) */
#define I2C_OAR1 (0x00000010)
#define I2C_OAR1_RESET_VALUE (0x00)
#define I2C_OAR1_RESET_UMASK (0x00)
#define I2C_OAR1_ADD_MASK (0xFF)
/* OAR2 (Own Address Register 2) 8bit (R/W) */
#define I2C_OAR2 (0x00000014)
#define I2C_OAR2_RESET_VALUE (0x40)
#define I2C_OAR2_RESET_UMASK (0x19)
#define I2C_OAR2_MASK (0xE6)
#define I2C_OAR2_FR_25_10MHZ (0x00)
#define I2C_OAR2_FR_10_1667MHZ (0x20)
#define I2C_OAR2_FR_1667_2667MHZ (0x40)
#define I2C_OAR2_FR_2667_40MHZ (0x60)
#define I2C_OAR2_FR_40_5333MHZ (0x80)
#define I2C_OAR2_FR_5333_66MHZ (0xA0)
#define I2C_OAR2_FR_66_80MHZ (0xC0)
#define I2C_OAR2_FR_80_100MHZ (0xE0)
#define I2C_OAR2_FR_MASK (0xE0)
#define I2C_OAR2_ADD_MASK (0x06)
/* DR (Data Register) 8bit (R/W) */
#define I2C_DR (0x00000018)
#define I2C_DR_RESET_VALUE (0x00)
#define I2C_DR_RESET_UMASK (0xFF)
#define I2C_DR_D_MASK (0xFF)
/* ECCR (Extended Clock Control Register) 8bit (R/W) */
#define I2C_ECCR (0x0000001C)
#define I2C_ECCR_RESET_VALUE (0x00)
#define I2C_ECCR_RESET_UMASK (0xE0)
#define I2C_ECCR_MASK (0x1F)
#define I2C_ECCR_CC_MASK (0x1F)
/*
* These events are more or less responses to commands
* sent into the hardware, presumably reflecting the state
* of an internal state machine.
*/
enum stu300_event {
STU300_EVENT_NONE = 0,
STU300_EVENT_1,
STU300_EVENT_2,
STU300_EVENT_3,
STU300_EVENT_4,
STU300_EVENT_5,
STU300_EVENT_6,
STU300_EVENT_7,
STU300_EVENT_8,
STU300_EVENT_9
};
enum stu300_error {
STU300_ERROR_NONE = 0,
STU300_ERROR_ACKNOWLEDGE_FAILURE,
STU300_ERROR_BUS_ERROR,
STU300_ERROR_ARBITRATION_LOST,
STU300_ERROR_UNKNOWN
};
/* timeout waiting for the controller to respond */
#define STU300_TIMEOUT (msecs_to_jiffies(1000))
/*
* The number of address send athemps tried before giving up.
* If the first one failes it seems like 5 to 8 attempts are required.
*/
#define NUM_ADDR_RESEND_ATTEMPTS 12
/* I2C clock speed, in Hz 0-400kHz*/
static unsigned int scl_frequency = 100000;
module_param(scl_frequency, uint, 0644);
/**
* struct stu300_dev - the stu300 driver state holder
* @pdev: parent platform device
* @adapter: corresponding I2C adapter
* @clk: hardware block clock
* @irq: assigned interrupt line
* @cmd_issue_lock: this locks the following cmd_ variables
* @cmd_complete: acknowledge completion for an I2C command
* @cmd_event: expected event coming in as a response to a command
* @cmd_err: error code as response to a command
* @speed: current bus speed in Hz
* @msg_index: index of current message
* @msg_len: length of current message
*/
struct stu300_dev {
struct platform_device *pdev;
struct i2c_adapter adapter;
void __iomem *virtbase;
struct clk *clk;
int irq;
spinlock_t cmd_issue_lock;
struct completion cmd_complete;
enum stu300_event cmd_event;
enum stu300_error cmd_err;
unsigned int speed;
int msg_index;
int msg_len;
};
/* Local forward function declarations */
static int stu300_init_hw(struct stu300_dev *dev);
/*
* The block needs writes in both MSW and LSW in order
* for all data lines to reach their destination.
*/
static inline void stu300_wr8(u32 value, void __iomem *address)
{
writel((value << 16) | value, address);
}
/*
* This merely masks off the duplicates which appear
* in bytes 1-3. You _MUST_ use 32-bit bus access on this
* device, else it will not work.
*/
static inline u32 stu300_r8(void __iomem *address)
{
return readl(address) & 0x000000FFU;
}
static void stu300_irq_enable(struct stu300_dev *dev)
{
u32 val;
val = stu300_r8(dev->virtbase + I2C_CR);
val |= I2C_CR_INTERRUPT_ENABLE;
/* Twice paranoia (possible HW glitch) */
stu300_wr8(val, dev->virtbase + I2C_CR);
stu300_wr8(val, dev->virtbase + I2C_CR);
}
static void stu300_irq_disable(struct stu300_dev *dev)
{
u32 val;
val = stu300_r8(dev->virtbase + I2C_CR);
val &= ~I2C_CR_INTERRUPT_ENABLE;
/* Twice paranoia (possible HW glitch) */
stu300_wr8(val, dev->virtbase + I2C_CR);
stu300_wr8(val, dev->virtbase + I2C_CR);
}
/*
* Tells whether a certain event or events occurred in
* response to a command. The events represent states in
* the internal state machine of the hardware. The events
* are not very well described in the hardware
* documentation and can only be treated as abstract state
* machine states.
*
* @ret 0 = event has not occurred or unknown error, any
* other value means the correct event occurred or an error.
*/
static int stu300_event_occurred(struct stu300_dev *dev,
enum stu300_event mr_event) {
u32 status1;
u32 status2;
/* What event happened? */
status1 = stu300_r8(dev->virtbase + I2C_SR1);
if (!(status1 & I2C_SR1_EVF_IND))
/* No event at all */
return 0;
status2 = stu300_r8(dev->virtbase + I2C_SR2);
/* Block any multiple interrupts */
stu300_irq_disable(dev);
/* Check for errors first */
if (status2 & I2C_SR2_AF_IND) {
dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
return 1;
} else if (status2 & I2C_SR2_BERR_IND) {
dev->cmd_err = STU300_ERROR_BUS_ERROR;
return 1;
} else if (status2 & I2C_SR2_ARLO_IND) {
dev->cmd_err = STU300_ERROR_ARBITRATION_LOST;
return 1;
}
switch (mr_event) {
case STU300_EVENT_1:
if (status1 & I2C_SR1_ADSL_IND)
return 1;
break;
case STU300_EVENT_2:
case STU300_EVENT_3:
case STU300_EVENT_7:
case STU300_EVENT_8:
if (status1 & I2C_SR1_BTF_IND) {
return 1;
}
break;
case STU300_EVENT_4:
if (status2 & I2C_SR2_STOPF_IND)
return 1;
break;
case STU300_EVENT_5:
if (status1 & I2C_SR1_SB_IND)
/* Clear start bit */
return 1;
break;
case STU300_EVENT_6:
if (status2 & I2C_SR2_ENDAD_IND) {
/* First check for any errors */
return 1;
}
break;
case STU300_EVENT_9:
if (status1 & I2C_SR1_ADD10_IND)
return 1;
break;
default:
break;
}
/* If we get here, we're on thin ice.
* Here we are in a status where we have
* gotten a response that does not match
* what we requested.
*/
dev->cmd_err = STU300_ERROR_UNKNOWN;
dev_err(&dev->pdev->dev,
"Unhandled interrupt! %d sr1: 0x%x sr2: 0x%x\n",
mr_event, status1, status2);
return 0;
}
static irqreturn_t stu300_irh(int irq, void *data)
{
struct stu300_dev *dev = data;
int res;
/* Just make sure that the block is clocked */
clk_enable(dev->clk);
/* See if this was what we were waiting for */
spin_lock(&dev->cmd_issue_lock);
res = stu300_event_occurred(dev, dev->cmd_event);
if (res || dev->cmd_err != STU300_ERROR_NONE)
complete(&dev->cmd_complete);
spin_unlock(&dev->cmd_issue_lock);
clk_disable(dev->clk);
return IRQ_HANDLED;
}
/*
* Sends a command and then waits for the bits masked by *flagmask*
* to go high or low by IRQ awaiting.
*/
static int stu300_start_and_await_event(struct stu300_dev *dev,
u8 cr_value,
enum stu300_event mr_event)
{
int ret;
if (unlikely(irqs_disabled())) {
/* TODO: implement polling for this case if need be. */
WARN(1, "irqs are disabled, cannot poll for event\n");
return -EIO;
}
/* Lock command issue, fill in an event we wait for */
spin_lock_irq(&dev->cmd_issue_lock);
init_completion(&dev->cmd_complete);
dev->cmd_err = STU300_ERROR_NONE;
dev->cmd_event = mr_event;
spin_unlock_irq(&dev->cmd_issue_lock);
/* Turn on interrupt, send command and wait. */
cr_value |= I2C_CR_INTERRUPT_ENABLE;
stu300_wr8(cr_value, dev->virtbase + I2C_CR);
ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
STU300_TIMEOUT);
if (ret < 0) {
dev_err(&dev->pdev->dev,
"wait_for_completion_interruptible_timeout() "
"returned %d waiting for event %04x\n", ret, mr_event);
return ret;
}
if (ret == 0) {
dev_err(&dev->pdev->dev, "controller timed out "
"waiting for event %d, reinit hardware\n", mr_event);
(void) stu300_init_hw(dev);
return -ETIMEDOUT;
}
if (dev->cmd_err != STU300_ERROR_NONE) {
dev_err(&dev->pdev->dev, "controller (start) "
"error %d waiting for event %d, reinit hardware\n",
dev->cmd_err, mr_event);
(void) stu300_init_hw(dev);
return -EIO;
}
return 0;
}
/*
* This waits for a flag to be set, if it is not set on entry, an interrupt is
* configured to wait for the flag using a completion.
*/
static int stu300_await_event(struct stu300_dev *dev,
enum stu300_event mr_event)
{
int ret;
if (unlikely(irqs_disabled())) {
/* TODO: implement polling for this case if need be. */
dev_err(&dev->pdev->dev, "irqs are disabled on this "
"system!\n");
return -EIO;
}
/* Is it already here? */
spin_lock_irq(&dev->cmd_issue_lock);
dev->cmd_err = STU300_ERROR_NONE;
dev->cmd_event = mr_event;
init_completion(&dev->cmd_complete);
/* Turn on the I2C interrupt for current operation */
stu300_irq_enable(dev);
/* Unlock the command block and wait for the event to occur */
spin_unlock_irq(&dev->cmd_issue_lock);
ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
STU300_TIMEOUT);
if (ret < 0) {
dev_err(&dev->pdev->dev,
"wait_for_completion_interruptible_timeout()"
"returned %d waiting for event %04x\n", ret, mr_event);
return ret;
}
if (ret == 0) {
if (mr_event != STU300_EVENT_6) {
dev_err(&dev->pdev->dev, "controller "
"timed out waiting for event %d, reinit "
"hardware\n", mr_event);
(void) stu300_init_hw(dev);
}
return -ETIMEDOUT;
}
if (dev->cmd_err != STU300_ERROR_NONE) {
if (mr_event != STU300_EVENT_6) {
dev_err(&dev->pdev->dev, "controller "
"error (await_event) %d waiting for event %d, "
"reinit hardware\n", dev->cmd_err, mr_event);
(void) stu300_init_hw(dev);
}
return -EIO;
}
return 0;
}
/*
* Waits for the busy bit to go low by repeated polling.
*/
#define BUSY_RELEASE_ATTEMPTS 10
static int stu300_wait_while_busy(struct stu300_dev *dev)
{
unsigned long timeout;
int i;
for (i = 0; i < BUSY_RELEASE_ATTEMPTS; i++) {
timeout = jiffies + STU300_TIMEOUT;
while (!time_after(jiffies, timeout)) {
/* Is not busy? */
if ((stu300_r8(dev->virtbase + I2C_SR1) &
I2C_SR1_BUSY_IND) == 0)
return 0;
msleep(1);
}
dev_err(&dev->pdev->dev, "transaction timed out "
"waiting for device to be free (not busy). "
"Attempt: %d\n", i+1);
dev_err(&dev->pdev->dev, "base address = "
"0x%08x, reinit hardware\n", (u32) dev->virtbase);
(void) stu300_init_hw(dev);
}
dev_err(&dev->pdev->dev, "giving up after %d attempts "
"to reset the bus.\n", BUSY_RELEASE_ATTEMPTS);
return -ETIMEDOUT;
}
struct stu300_clkset {
unsigned long rate;
u32 setting;
};
static const struct stu300_clkset stu300_clktable[] = {
{ 0, 0xFFU },
{ 2500000, I2C_OAR2_FR_25_10MHZ },
{ 10000000, I2C_OAR2_FR_10_1667MHZ },
{ 16670000, I2C_OAR2_FR_1667_2667MHZ },
{ 26670000, I2C_OAR2_FR_2667_40MHZ },
{ 40000000, I2C_OAR2_FR_40_5333MHZ },
{ 53330000, I2C_OAR2_FR_5333_66MHZ },
{ 66000000, I2C_OAR2_FR_66_80MHZ },
{ 80000000, I2C_OAR2_FR_80_100MHZ },
{ 100000000, 0xFFU },
};
static int stu300_set_clk(struct stu300_dev *dev, unsigned long clkrate)
{
u32 val;
int i = 0;
/* Locate the appropriate clock setting */
while (i < ARRAY_SIZE(stu300_clktable) - 1 &&
stu300_clktable[i].rate < clkrate)
i++;
if (stu300_clktable[i].setting == 0xFFU) {
dev_err(&dev->pdev->dev, "too %s clock rate requested "
"(%lu Hz).\n", i ? "high" : "low", clkrate);
return -EINVAL;
}
stu300_wr8(stu300_clktable[i].setting,
dev->virtbase + I2C_OAR2);
dev_dbg(&dev->pdev->dev, "Clock rate %lu Hz, I2C bus speed %d Hz "
"virtbase %p\n", clkrate, dev->speed, dev->virtbase);
if (dev->speed > 100000)
/* Fast Mode I2C */
val = ((clkrate/dev->speed) - 9)/3 + 1;
else
/* Standard Mode I2C */
val = ((clkrate/dev->speed) - 7)/2 + 1;
/* According to spec the divider must be > 2 */
if (val < 0x002) {
dev_err(&dev->pdev->dev, "too low clock rate (%lu Hz).\n",
clkrate);
return -EINVAL;
}
/* We have 12 bits clock divider only! */
if (val & 0xFFFFF000U) {
dev_err(&dev->pdev->dev, "too high clock rate (%lu Hz).\n",
clkrate);
return -EINVAL;
}
if (dev->speed > 100000) {
/* CC6..CC0 */
stu300_wr8((val & I2C_CCR_CC_MASK) | I2C_CCR_FMSM,
dev->virtbase + I2C_CCR);
dev_dbg(&dev->pdev->dev, "set clock divider to 0x%08x, "
"Fast Mode I2C\n", val);
} else {
/* CC6..CC0 */
stu300_wr8((val & I2C_CCR_CC_MASK),
dev->virtbase + I2C_CCR);
dev_dbg(&dev->pdev->dev, "set clock divider to "
"0x%08x, Standard Mode I2C\n", val);
}
/* CC11..CC7 */
stu300_wr8(((val >> 7) & 0x1F),
dev->virtbase + I2C_ECCR);
return 0;
}
static int stu300_init_hw(struct stu300_dev *dev)
{
u32 dummy;
unsigned long clkrate;
int ret;
/* Disable controller */
stu300_wr8(0x00, dev->virtbase + I2C_CR);
/*
* Set own address to some default value (0x00).
* We do not support slave mode anyway.
*/
stu300_wr8(0x00, dev->virtbase + I2C_OAR1);
/*
* The I2C controller only operates properly in 26 MHz but we
* program this driver as if we didn't know. This will also set the two
* high bits of the own address to zero as well.
* There is no known hardware issue with running in 13 MHz
* However, speeds over 200 kHz are not used.
*/
clkrate = clk_get_rate(dev->clk);
ret = stu300_set_clk(dev, clkrate);
if (ret)
return ret;
/*
* Enable block, do it TWICE (hardware glitch)
* Setting bit 7 can enable DDC mode. (Not used currently.)
*/
stu300_wr8(I2C_CR_PERIPHERAL_ENABLE,
dev->virtbase + I2C_CR);
stu300_wr8(I2C_CR_PERIPHERAL_ENABLE,
dev->virtbase + I2C_CR);
/* Make a dummy read of the status register SR1 & SR2 */
dummy = stu300_r8(dev->virtbase + I2C_SR2);
dummy = stu300_r8(dev->virtbase + I2C_SR1);
return 0;
}
/* Send slave address. */
static int stu300_send_address(struct stu300_dev *dev,
struct i2c_msg *msg, int resend)
{
u32 val;
int ret;
if (msg->flags & I2C_M_TEN)
/* This is probably how 10 bit addresses look */
val = (0xf0 | (((u32) msg->addr & 0x300) >> 7)) &
I2C_DR_D_MASK;
else
val = ((msg->addr << 1) & I2C_DR_D_MASK);
if (msg->flags & I2C_M_RD) {
/* This is the direction bit */
val |= 0x01;
if (resend)
dev_dbg(&dev->pdev->dev, "read resend\n");
} else if (resend)
dev_dbg(&dev->pdev->dev, "write resend\n");
stu300_wr8(val, dev->virtbase + I2C_DR);
/* For 10bit addressing, await 10bit request (EVENT 9) */
if (msg->flags & I2C_M_TEN) {
ret = stu300_await_event(dev, STU300_EVENT_9);
/*
* The slave device wants a 10bit address, send the rest
* of the bits (the LSBits)
*/
val = msg->addr & I2C_DR_D_MASK;
/* This clears "event 9" */
stu300_wr8(val, dev->virtbase + I2C_DR);
if (ret != 0)
return ret;
}
/* FIXME: Why no else here? two events for 10bit?
* Await event 6 (normal) or event 9 (10bit)
*/
if (resend)
dev_dbg(&dev->pdev->dev, "await event 6\n");
ret = stu300_await_event(dev, STU300_EVENT_6);
/*
* Clear any pending EVENT 6 no matter what happened during
* await_event.
*/
val = stu300_r8(dev->virtbase + I2C_CR);
val |= I2C_CR_PERIPHERAL_ENABLE;
stu300_wr8(val, dev->virtbase + I2C_CR);
return ret;
}
static int stu300_xfer_msg(struct i2c_adapter *adap,
struct i2c_msg *msg, int stop)
{
u32 cr;
u32 val;
u32 i;
int ret;
int attempts = 0;
struct stu300_dev *dev = i2c_get_adapdata(adap);
clk_enable(dev->clk);
/* Remove this if (0) to trace each and every message. */
if (0) {
dev_dbg(&dev->pdev->dev, "I2C message to: 0x%04x, len: %d, "
"flags: 0x%04x, stop: %d\n",
msg->addr, msg->len, msg->flags, stop);
}
/* Zero-length messages are not supported by this hardware */
if (msg->len == 0) {
ret = -EINVAL;
goto exit_disable;
}
/*
* For some reason, sending the address sometimes fails when running
* on the 13 MHz clock. No interrupt arrives. This is a work around,
* which tries to restart and send the address up to 10 times before
* really giving up. Usually 5 to 8 attempts are enough.
*/
do {
if (attempts)
dev_dbg(&dev->pdev->dev, "wait while busy\n");
/* Check that the bus is free, or wait until some timeout */
ret = stu300_wait_while_busy(dev);
if (ret != 0)
goto exit_disable;
if (attempts)
dev_dbg(&dev->pdev->dev, "re-int hw\n");
/*
* According to ST, there is no problem if the clock is
* changed between 13 and 26 MHz during a transfer.
*/
ret = stu300_init_hw(dev);
if (ret)
goto exit_disable;
/* Send a start condition */
cr = I2C_CR_PERIPHERAL_ENABLE;
/* Setting the START bit puts the block in master mode */
if (!(msg->flags & I2C_M_NOSTART))
cr |= I2C_CR_START_ENABLE;
if ((msg->flags & I2C_M_RD) && (msg->len > 1))
/* On read more than 1 byte, we need ack. */
cr |= I2C_CR_ACK_ENABLE;
/* Check that it gets through */
if (!(msg->flags & I2C_M_NOSTART)) {
if (attempts)
dev_dbg(&dev->pdev->dev, "send start event\n");
ret = stu300_start_and_await_event(dev, cr,
STU300_EVENT_5);
}
if (attempts)
dev_dbg(&dev->pdev->dev, "send address\n");
if (ret == 0)
/* Send address */
ret = stu300_send_address(dev, msg, attempts != 0);
if (ret != 0) {
attempts++;
dev_dbg(&dev->pdev->dev, "failed sending address, "
"retrying. Attempt: %d msg_index: %d/%d\n",
attempts, dev->msg_index, dev->msg_len);
}
} while (ret != 0 && attempts < NUM_ADDR_RESEND_ATTEMPTS);
if (attempts < NUM_ADDR_RESEND_ATTEMPTS && attempts > 0) {
dev_dbg(&dev->pdev->dev, "managed to get address "
"through after %d attempts\n", attempts);
} else if (attempts == NUM_ADDR_RESEND_ATTEMPTS) {
dev_dbg(&dev->pdev->dev, "I give up, tried %d times "
"to resend address.\n",
NUM_ADDR_RESEND_ATTEMPTS);
goto exit_disable;
}
if (msg->flags & I2C_M_RD) {
/* READ: we read the actual bytes one at a time */
for (i = 0; i < msg->len; i++) {
if (i == msg->len-1) {
/*
* Disable ACK and set STOP condition before
* reading last byte
*/
val = I2C_CR_PERIPHERAL_ENABLE;
if (stop)
val |= I2C_CR_STOP_ENABLE;
stu300_wr8(val,
dev->virtbase + I2C_CR);
}
/* Wait for this byte... */
ret = stu300_await_event(dev, STU300_EVENT_7);
if (ret != 0)
goto exit_disable;
/* This clears event 7 */
msg->buf[i] = (u8) stu300_r8(dev->virtbase + I2C_DR);
}
} else {
/* WRITE: we send the actual bytes one at a time */
for (i = 0; i < msg->len; i++) {
/* Write the byte */
stu300_wr8(msg->buf[i],
dev->virtbase + I2C_DR);
/* Check status */
ret = stu300_await_event(dev, STU300_EVENT_8);
/* Next write to DR will clear event 8 */
if (ret != 0) {
dev_err(&dev->pdev->dev, "error awaiting "
"event 8 (%d)\n", ret);
goto exit_disable;
}
}
/* Check NAK */
if (!(msg->flags & I2C_M_IGNORE_NAK)) {
if (stu300_r8(dev->virtbase + I2C_SR2) &
I2C_SR2_AF_IND) {
dev_err(&dev->pdev->dev, "I2C payload "
"send returned NAK!\n");
ret = -EIO;
goto exit_disable;
}
}
if (stop) {
/* Send stop condition */
val = I2C_CR_PERIPHERAL_ENABLE;
val |= I2C_CR_STOP_ENABLE;
stu300_wr8(val, dev->virtbase + I2C_CR);
}
}
/* Check that the bus is free, or wait until some timeout occurs */
ret = stu300_wait_while_busy(dev);
if (ret != 0) {
dev_err(&dev->pdev->dev, "timout waiting for transfer "
"to commence.\n");
goto exit_disable;
}
/* Dummy read status registers */
val = stu300_r8(dev->virtbase + I2C_SR2);
val = stu300_r8(dev->virtbase + I2C_SR1);
ret = 0;
exit_disable:
/* Disable controller */
stu300_wr8(0x00, dev->virtbase + I2C_CR);
clk_disable(dev->clk);
return ret;
}
static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
int ret = -1;
int i;
struct stu300_dev *dev = i2c_get_adapdata(adap);
dev->msg_len = num;
for (i = 0; i < num; i++) {
/*
* Another driver appears to send stop for each message,
* here we only do that for the last message. Possibly some
* peripherals require this behaviour, then their drivers
* have to send single messages in order to get "stop" for
* each message.
*/
dev->msg_index = i;
ret = stu300_xfer_msg(adap, &msgs[i], (i == (num - 1)));
if (ret != 0) {
num = ret;
break;
}
}
return num;
}
static u32 stu300_func(struct i2c_adapter *adap)
{
/* This is the simplest thing you can think of... */
return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR;
}
static const struct i2c_algorithm stu300_algo = {
.master_xfer = stu300_xfer,
.functionality = stu300_func,
};
static int __init
stu300_probe(struct platform_device *pdev)
{
struct stu300_dev *dev;
struct i2c_adapter *adap;
struct resource *res;
int bus_nr;
int ret = 0;
dev = devm_kzalloc(&pdev->dev, sizeof(struct stu300_dev), GFP_KERNEL);
if (!dev) {
dev_err(&pdev->dev, "could not allocate device struct\n");
return -ENOMEM;
}
bus_nr = pdev->id;
dev->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(dev->clk)) {
dev_err(&pdev->dev, "could not retrieve i2c bus clock\n");
return PTR_ERR(dev->clk);
}
dev->pdev = pdev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENOENT;
dev->virtbase = devm_ioremap_resource(&pdev->dev, res);
dev_dbg(&pdev->dev, "initialize bus device I2C%d on virtual "
"base %p\n", bus_nr, dev->virtbase);
if (IS_ERR(dev->virtbase))
return PTR_ERR(dev->virtbase);
dev->irq = platform_get_irq(pdev, 0);
ret = devm_request_irq(&pdev->dev, dev->irq, stu300_irh, 0, NAME, dev);
if (ret < 0)
return ret;
dev->speed = scl_frequency;
clk_prepare_enable(dev->clk);
ret = stu300_init_hw(dev);
clk_disable(dev->clk);
if (ret != 0) {
dev_err(&dev->pdev->dev, "error initializing hardware.\n");
return -EIO;
}
/* IRQ event handling initialization */
spin_lock_init(&dev->cmd_issue_lock);
dev->cmd_event = STU300_EVENT_NONE;
dev->cmd_err = STU300_ERROR_NONE;
adap = &dev->adapter;
adap->owner = THIS_MODULE;
/* DDC class but actually often used for more generic I2C */
adap->class = I2C_CLASS_DDC;
strlcpy(adap->name, "ST Microelectronics DDC I2C adapter",
sizeof(adap->name));
adap->nr = bus_nr;
adap->algo = &stu300_algo;
adap->dev.parent = &pdev->dev;
adap->dev.of_node = pdev->dev.of_node;
i2c_set_adapdata(adap, dev);
/* i2c device drivers may be active on return from add_adapter() */
ret = i2c_add_numbered_adapter(adap);
if (ret) {
dev_err(&pdev->dev, "failure adding ST Micro DDC "
"I2C adapter\n");
return ret;
}
platform_set_drvdata(pdev, dev);
dev_info(&pdev->dev, "ST DDC I2C @ %p, irq %d\n",
dev->virtbase, dev->irq);
of_i2c_register_devices(adap);
return 0;
}
#ifdef CONFIG_PM
static int stu300_suspend(struct device *device)
{
struct stu300_dev *dev = dev_get_drvdata(device);
/* Turn off everything */
stu300_wr8(0x00, dev->virtbase + I2C_CR);
return 0;
}
static int stu300_resume(struct device *device)
{
int ret = 0;
struct stu300_dev *dev = dev_get_drvdata(device);
clk_enable(dev->clk);
ret = stu300_init_hw(dev);
clk_disable(dev->clk);
if (ret != 0)
dev_err(device, "error re-initializing hardware.\n");
return ret;
}
static SIMPLE_DEV_PM_OPS(stu300_pm, stu300_suspend, stu300_resume);
#define STU300_I2C_PM (&stu300_pm)
#else
#define STU300_I2C_PM NULL
#endif
static int __exit
stu300_remove(struct platform_device *pdev)
{
struct stu300_dev *dev = platform_get_drvdata(pdev);
i2c_del_adapter(&dev->adapter);
/* Turn off everything */
stu300_wr8(0x00, dev->virtbase + I2C_CR);
return 0;
}
static const struct of_device_id stu300_dt_match[] = {
{ .compatible = "st,ddci2c" },
{},
};
static struct platform_driver stu300_i2c_driver = {
.driver = {
.name = NAME,
.owner = THIS_MODULE,
.pm = STU300_I2C_PM,
.of_match_table = stu300_dt_match,
},
.remove = __exit_p(stu300_remove),
};
static int __init stu300_init(void)
{
return platform_driver_probe(&stu300_i2c_driver, stu300_probe);
}
static void __exit stu300_exit(void)
{
platform_driver_unregister(&stu300_i2c_driver);
}
/*
* The systems using this bus often have very basic devices such
* as regulators on the I2C bus, so this needs to be loaded early.
* Therefore it is registered in the subsys_initcall().
*/
subsys_initcall(stu300_init);
module_exit(stu300_exit);
MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
MODULE_DESCRIPTION("ST Micro DDC I2C adapter (" NAME ")");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" NAME);
