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Diffstat (limited to 'drivers/i2c/busses/i2c-exynos5.c')
-rw-r--r--drivers/i2c/busses/i2c-exynos5.c63
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.