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path: root/drivers/i2c/busses/i2c-omap.c
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Diffstat (limited to 'drivers/i2c/busses/i2c-omap.c')
-rw-r--r--drivers/i2c/busses/i2c-omap.c136
1 files changed, 127 insertions, 9 deletions
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 277a2288d4a8..0e894193accf 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -54,6 +54,9 @@
/* timeout for pm runtime autosuspend */
#define OMAP_I2C_PM_TIMEOUT 1000 /* ms */
+/* timeout for making decision on bus free status */
+#define OMAP_I2C_BUS_FREE_TIMEOUT (msecs_to_jiffies(10))
+
/* For OMAP3 I2C_IV has changed to I2C_WE (wakeup enable) */
enum {
OMAP_I2C_REV_REG = 0,
@@ -98,7 +101,7 @@ enum {
#define OMAP_I2C_STAT_ROVR (1 << 11) /* Receive overrun */
#define OMAP_I2C_STAT_XUDF (1 << 10) /* Transmit underflow */
#define OMAP_I2C_STAT_AAS (1 << 9) /* Address as slave */
-#define OMAP_I2C_STAT_AD0 (1 << 8) /* Address zero */
+#define OMAP_I2C_STAT_BF (1 << 8) /* Bus Free */
#define OMAP_I2C_STAT_XRDY (1 << 4) /* Transmit data ready */
#define OMAP_I2C_STAT_RRDY (1 << 3) /* Receive data ready */
#define OMAP_I2C_STAT_ARDY (1 << 2) /* Register access ready */
@@ -146,16 +149,20 @@ enum {
#define OMAP_I2C_SCLH_HSSCLH 8
/* I2C System Test Register (OMAP_I2C_SYSTEST): */
-#ifdef DEBUG
#define OMAP_I2C_SYSTEST_ST_EN (1 << 15) /* System test enable */
#define OMAP_I2C_SYSTEST_FREE (1 << 14) /* Free running mode */
#define OMAP_I2C_SYSTEST_TMODE_MASK (3 << 12) /* Test mode select */
#define OMAP_I2C_SYSTEST_TMODE_SHIFT (12) /* Test mode select */
+/* Functional mode */
+#define OMAP_I2C_SYSTEST_SCL_I_FUNC (1 << 8) /* SCL line input value */
+#define OMAP_I2C_SYSTEST_SCL_O_FUNC (1 << 7) /* SCL line output value */
+#define OMAP_I2C_SYSTEST_SDA_I_FUNC (1 << 6) /* SDA line input value */
+#define OMAP_I2C_SYSTEST_SDA_O_FUNC (1 << 5) /* SDA line output value */
+/* SDA/SCL IO mode */
#define OMAP_I2C_SYSTEST_SCL_I (1 << 3) /* SCL line sense in */
#define OMAP_I2C_SYSTEST_SCL_O (1 << 2) /* SCL line drive out */
#define OMAP_I2C_SYSTEST_SDA_I (1 << 1) /* SDA line sense in */
#define OMAP_I2C_SYSTEST_SDA_O (1 << 0) /* SDA line drive out */
-#endif
/* OCP_SYSSTATUS bit definitions */
#define SYSS_RESETDONE_MASK (1 << 0)
@@ -202,6 +209,9 @@ struct omap_i2c_dev {
*/
u32 rev;
unsigned b_hw:1; /* bad h/w fixes */
+ unsigned bb_valid:1; /* true when BB-bit reflects
+ * the I2C bus state
+ */
unsigned receiver:1; /* true when we're in receiver mode */
u16 iestate; /* Saved interrupt register */
u16 pscstate;
@@ -290,6 +300,12 @@ static void __omap_i2c_init(struct omap_i2c_dev *dev)
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
/*
+ * NOTE: right after setting CON_EN, STAT_BB could be 0 while the
+ * bus is busy. It will be changed to 1 on the next IP FCLK clock.
+ * udelay(1) will be enough to fix that.
+ */
+
+ /*
* Don't write to this register if the IE state is 0 as it can
* cause deadlock.
*/
@@ -328,7 +344,12 @@ static int omap_i2c_reset(struct omap_i2c_dev *dev)
/* SYSC register is cleared by the reset; rewrite it */
omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, sysc);
+ if (dev->rev > OMAP_I2C_REV_ON_3430_3530) {
+ /* Schedule I2C-bus monitoring on the next transfer */
+ dev->bb_valid = 0;
+ }
}
+
return 0;
}
@@ -441,6 +462,11 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
dev->scllstate = scll;
dev->sclhstate = sclh;
+ if (dev->rev <= OMAP_I2C_REV_ON_3430_3530) {
+ /* Not implemented */
+ dev->bb_valid = 1;
+ }
+
__omap_i2c_init(dev);
return 0;
@@ -465,6 +491,91 @@ static int omap_i2c_wait_for_bb(struct omap_i2c_dev *dev)
return 0;
}
+/*
+ * Wait while BB-bit doesn't reflect the I2C bus state
+ *
+ * In a multimaster environment, after IP software reset, BB-bit value doesn't
+ * correspond to the current bus state. It may happen what BB-bit will be 0,
+ * while the bus is busy due to another I2C master activity.
+ * Here are BB-bit values after reset:
+ * SDA SCL BB NOTES
+ * 0 0 0 1, 2
+ * 1 0 0 1, 2
+ * 0 1 1
+ * 1 1 0 3
+ * Later, if IP detect SDA=0 and SCL=1 (ACK) or SDA 1->0 while SCL=1 (START)
+ * combinations on the bus, it set BB-bit to 1.
+ * If IP detect SDA 0->1 while SCL=1 (STOP) combination on the bus,
+ * it set BB-bit to 0 and BF to 1.
+ * BB and BF bits correctly tracks the bus state while IP is suspended
+ * BB bit became valid on the next FCLK clock after CON_EN bit set
+ *
+ * NOTES:
+ * 1. Any transfer started when BB=0 and bus is busy wouldn't be
+ * completed by IP and results in controller timeout.
+ * 2. Any transfer started when BB=0 and SCL=0 results in IP
+ * starting to drive SDA low. In that case IP corrupt data
+ * on the bus.
+ * 3. Any transfer started in the middle of another master's transfer
+ * results in unpredictable results and data corruption
+ */
+static int omap_i2c_wait_for_bb_valid(struct omap_i2c_dev *dev)
+{
+ unsigned long bus_free_timeout = 0;
+ unsigned long timeout;
+ int bus_free = 0;
+ u16 stat, systest;
+
+ if (dev->bb_valid)
+ return 0;
+
+ timeout = jiffies + OMAP_I2C_TIMEOUT;
+ while (1) {
+ stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
+ /*
+ * We will see BB or BF event in a case IP had detected any
+ * activity on the I2C bus. Now IP correctly tracks the bus
+ * state. BB-bit value is valid.
+ */
+ if (stat & (OMAP_I2C_STAT_BB | OMAP_I2C_STAT_BF))
+ break;
+
+ /*
+ * Otherwise, we must look signals on the bus to make
+ * the right decision.
+ */
+ systest = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
+ if ((systest & OMAP_I2C_SYSTEST_SCL_I_FUNC) &&
+ (systest & OMAP_I2C_SYSTEST_SDA_I_FUNC)) {
+ if (!bus_free) {
+ bus_free_timeout = jiffies +
+ OMAP_I2C_BUS_FREE_TIMEOUT;
+ bus_free = 1;
+ }
+
+ /*
+ * SDA and SCL lines was high for 10 ms without bus
+ * activity detected. The bus is free. Consider
+ * BB-bit value is valid.
+ */
+ if (time_after(jiffies, bus_free_timeout))
+ break;
+ } else {
+ bus_free = 0;
+ }
+
+ if (time_after(jiffies, timeout)) {
+ dev_warn(dev->dev, "timeout waiting for bus ready\n");
+ return -ETIMEDOUT;
+ }
+
+ msleep(1);
+ }
+
+ dev->bb_valid = 1;
+ return 0;
+}
+
static void omap_i2c_resize_fifo(struct omap_i2c_dev *dev, u8 size, bool is_rx)
{
u16 buf;
@@ -557,7 +668,11 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
if (!dev->b_hw && stop)
w |= OMAP_I2C_CON_STP;
-
+ /*
+ * NOTE: STAT_BB bit could became 1 here if another master occupy
+ * the bus. IP successfully complete transfer when the bus will be
+ * free again (BB reset to 0).
+ */
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
/*
@@ -600,13 +715,15 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
return 0;
/* We have an error */
- if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR |
- OMAP_I2C_STAT_XUDF)) {
+ if (dev->cmd_err & (OMAP_I2C_STAT_ROVR | OMAP_I2C_STAT_XUDF)) {
omap_i2c_reset(dev);
__omap_i2c_init(dev);
return -EIO;
}
+ if (dev->cmd_err & OMAP_I2C_STAT_AL)
+ return -EAGAIN;
+
if (dev->cmd_err & OMAP_I2C_STAT_NACK) {
if (msg->flags & I2C_M_IGNORE_NAK)
return 0;
@@ -635,6 +752,10 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
if (r < 0)
goto out;
+ r = omap_i2c_wait_for_bb_valid(dev);
+ if (r < 0)
+ goto out;
+
r = omap_i2c_wait_for_bb(dev);
if (r < 0)
goto out;
@@ -1280,7 +1401,6 @@ static int omap_i2c_remove(struct platform_device *pdev)
}
#ifdef CONFIG_PM
-#ifdef CONFIG_PM_RUNTIME
static int omap_i2c_runtime_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
@@ -1318,7 +1438,6 @@ static int omap_i2c_runtime_resume(struct device *dev)
return 0;
}
-#endif /* CONFIG_PM_RUNTIME */
static struct dev_pm_ops omap_i2c_pm_ops = {
SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend,
@@ -1334,7 +1453,6 @@ static struct platform_driver omap_i2c_driver = {
.remove = omap_i2c_remove,
.driver = {
.name = "omap_i2c",
- .owner = THIS_MODULE,
.pm = OMAP_I2C_PM_OPS,
.of_match_table = of_match_ptr(omap_i2c_of_match),
},
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-24 12:46:54 +0300