diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-exynos5.c | 63 |
1 files changed, 57 insertions, 6 deletions
diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c index b02428498f6d..12ec8484e653 100644 --- a/drivers/i2c/busses/i2c-exynos5.c +++ b/drivers/i2c/busses/i2c-exynos5.c @@ -128,6 +128,10 @@ #define HSI2C_TIMEOUT_EN (1u << 31) #define HSI2C_TIMEOUT_MASK 0xff +/* I2C_MANUAL_CMD register bits */ +#define HSI2C_CMD_READ_DATA (1u << 4) +#define HSI2C_CMD_SEND_STOP (1u << 2) + /* I2C_TRANS_STATUS register bits */ #define HSI2C_MASTER_BUSY (1u << 17) #define HSI2C_SLAVE_BUSY (1u << 16) @@ -441,12 +445,6 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id) i2c->state = -ETIMEDOUT; goto stop; } - - trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); - if ((trans_status & HSI2C_MASTER_ST_MASK) == HSI2C_MASTER_ST_LOSE) { - i2c->state = -EAGAIN; - goto stop; - } } else if (int_status & HSI2C_INT_I2C) { trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); if (trans_status & HSI2C_NO_DEV_ACK) { @@ -544,6 +542,57 @@ static int exynos5_i2c_wait_bus_idle(struct exynos5_i2c *i2c) return -EBUSY; } +static void exynos5_i2c_bus_recover(struct exynos5_i2c *i2c) +{ + u32 val; + + val = readl(i2c->regs + HSI2C_CTL) | HSI2C_RXCHON; + writel(val, i2c->regs + HSI2C_CTL); + val = readl(i2c->regs + HSI2C_CONF) & ~HSI2C_AUTO_MODE; + writel(val, i2c->regs + HSI2C_CONF); + + /* + * Specification says master should send nine clock pulses. It can be + * emulated by sending manual read command (nine pulses for read eight + * bits + one pulse for NACK). + */ + writel(HSI2C_CMD_READ_DATA, i2c->regs + HSI2C_MANUAL_CMD); + exynos5_i2c_wait_bus_idle(i2c); + writel(HSI2C_CMD_SEND_STOP, i2c->regs + HSI2C_MANUAL_CMD); + exynos5_i2c_wait_bus_idle(i2c); + + val = readl(i2c->regs + HSI2C_CTL) & ~HSI2C_RXCHON; + writel(val, i2c->regs + HSI2C_CTL); + val = readl(i2c->regs + HSI2C_CONF) | HSI2C_AUTO_MODE; + writel(val, i2c->regs + HSI2C_CONF); +} + +static void exynos5_i2c_bus_check(struct exynos5_i2c *i2c) +{ + unsigned long timeout; + + if (i2c->variant->hw != HSI2C_EXYNOS7) + return; + + /* + * HSI2C_MASTER_ST_LOSE state in EXYNOS7 variant before transaction + * indicates that bus is stuck (SDA is low). In such case bus recovery + * can be performed. + */ + timeout = jiffies + msecs_to_jiffies(100); + for (;;) { + u32 st = readl(i2c->regs + HSI2C_TRANS_STATUS); + + if ((st & HSI2C_MASTER_ST_MASK) != HSI2C_MASTER_ST_LOSE) + return; + + if (time_is_before_jiffies(timeout)) + return; + + exynos5_i2c_bus_recover(i2c); + } +} + /* * exynos5_i2c_message_start: Configures the bus and starts the xfer * i2c: struct exynos5_i2c pointer for the current bus @@ -598,6 +647,8 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop) writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL); writel(i2c_ctl, i2c->regs + HSI2C_CTL); + exynos5_i2c_bus_check(i2c); + /* * Enable interrupts before starting the transfer so that we don't * miss any INT_I2C interrupts. |