diff options
Diffstat (limited to 'kernel/drivers/i2c/busses/i2c-stu300.c')
| -rw-r--r-- | kernel/drivers/i2c/busses/i2c-stu300.c | 1013 |
1 files changed, 1013 insertions, 0 deletions
diff --git a/kernel/drivers/i2c/busses/i2c-stu300.c b/kernel/drivers/i2c/busses/i2c-stu300.c new file mode 100644 index 000000000..4885da9e9 --- /dev/null +++ b/kernel/drivers/i2c/busses/i2c-stu300.c @@ -0,0 +1,1013 @@ +/* + * 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> + +/* 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, "timeout 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 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) + 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); + 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_DEPRECATED; + 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); + + return 0; +} + +#ifdef CONFIG_PM_SLEEP +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 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, + .pm = STU300_I2C_PM, + .of_match_table = stu300_dt_match, + }, + .probe = stu300_probe, + .remove = stu300_remove, + +}; + +static int __init stu300_init(void) +{ + return platform_driver_register(&stu300_i2c_driver); +} + +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); |