Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2009-11-03 07:45:50 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-11-03 07:45:50 -0800
commit78e1e34056f6508a24d08a2a020cd7b124eacdc8 (patch)
tree6cc0d08ccb64fe58f5a933420663656ee3b09ffc
parent1cec2cdee4fe59e72f7e1662431264d97d863b9b (diff)
parent45da790ebe746bb29f7e4adf806c020db6ff7755 (diff)
Merge branch 'i2c-fixes' of git://git.fluff.org/bjdooks/linux
* 'i2c-fixes' of git://git.fluff.org/bjdooks/linux: i2c-mpc: Do not generate STOP after read. i2c: imx: disable clock when it's possible to save power. i2c: imx: only imx1 needs disable delay i2c: imx: check busy bit when START/STOP
-rw-r--r--drivers/i2c/busses/i2c-imx.c86
-rw-r--r--drivers/i2c/busses/i2c-mpc.c10
2 files changed, 59 insertions, 37 deletions
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 4afba3ec2a61..e3654d683e15 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -120,19 +120,26 @@ struct imx_i2c_struct {
wait_queue_head_t queue;
unsigned long i2csr;
unsigned int disable_delay;
+ int stopped;
+ unsigned int ifdr; /* IMX_I2C_IFDR */
};
/** Functions for IMX I2C adapter driver ***************************************
*******************************************************************************/
-static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
{
unsigned long orig_jiffies = jiffies;
+ unsigned int temp;
dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
- /* wait for bus not busy */
- while (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_IBB) {
+ while (1) {
+ temp = readb(i2c_imx->base + IMX_I2C_I2SR);
+ if (for_busy && (temp & I2SR_IBB))
+ break;
+ if (!for_busy && !(temp & I2SR_IBB))
+ break;
if (signal_pending(current)) {
dev_dbg(&i2c_imx->adapter.dev,
"<%s> I2C Interrupted\n", __func__);
@@ -179,41 +186,62 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
return 0;
}
-static void i2c_imx_start(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
{
unsigned int temp = 0;
+ int result;
dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
+ clk_enable(i2c_imx->clk);
+ writeb(i2c_imx->ifdr, i2c_imx->base + IMX_I2C_IFDR);
/* Enable I2C controller */
+ writeb(0, i2c_imx->base + IMX_I2C_I2SR);
writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
+
+ /* Wait controller to be stable */
+ udelay(50);
+
/* Start I2C transaction */
temp = readb(i2c_imx->base + IMX_I2C_I2CR);
temp |= I2CR_MSTA;
writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+ result = i2c_imx_bus_busy(i2c_imx, 1);
+ if (result)
+ return result;
+ i2c_imx->stopped = 0;
+
temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+ return result;
}
static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
{
unsigned int temp = 0;
- /* Stop I2C transaction */
- dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
- temp = readb(i2c_imx->base + IMX_I2C_I2CR);
- temp &= ~I2CR_MSTA;
- writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
- /* setup chip registers to defaults */
- writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
- writeb(0, i2c_imx->base + IMX_I2C_I2SR);
- /*
- * This delay caused by an i.MXL hardware bug.
- * If no (or too short) delay, no "STOP" bit will be generated.
- */
- udelay(i2c_imx->disable_delay);
+ if (!i2c_imx->stopped) {
+ /* Stop I2C transaction */
+ dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
+ temp = readb(i2c_imx->base + IMX_I2C_I2CR);
+ temp &= ~(I2CR_MSTA | I2CR_MTX);
+ writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+ i2c_imx->stopped = 1;
+ }
+ if (cpu_is_mx1()) {
+ /*
+ * This delay caused by an i.MXL hardware bug.
+ * If no (or too short) delay, no "STOP" bit will be generated.
+ */
+ udelay(i2c_imx->disable_delay);
+ }
+
+ if (!i2c_imx->stopped)
+ i2c_imx_bus_busy(i2c_imx, 0);
+
/* Disable I2C controller */
writeb(0, i2c_imx->base + IMX_I2C_I2CR);
+ clk_disable(i2c_imx->clk);
}
static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
@@ -233,8 +261,8 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
else
for (i = 0; i2c_clk_div[i][0] < div; i++);
- /* Write divider value to register */
- writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
+ /* Store divider value */
+ i2c_imx->ifdr = i2c_clk_div[i][1];
/*
* There dummy delay is calculated.
@@ -341,11 +369,15 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
if (result)
return result;
if (i == (msgs->len - 1)) {
+ /* It must generate STOP before read I2DR to prevent
+ controller from generating another clock cycle */
dev_dbg(&i2c_imx->adapter.dev,
"<%s> clear MSTA\n", __func__);
temp = readb(i2c_imx->base + IMX_I2C_I2CR);
- temp &= ~I2CR_MSTA;
+ temp &= ~(I2CR_MSTA | I2CR_MTX);
writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+ i2c_imx_bus_busy(i2c_imx, 0);
+ i2c_imx->stopped = 1;
} else if (i == (msgs->len - 2)) {
dev_dbg(&i2c_imx->adapter.dev,
"<%s> set TXAK\n", __func__);
@@ -370,14 +402,11 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
- /* Check if i2c bus is not busy */
- result = i2c_imx_bus_busy(i2c_imx);
+ /* Start I2C transfer */
+ result = i2c_imx_start(i2c_imx);
if (result)
goto fail0;
- /* Start I2C transfer */
- i2c_imx_start(i2c_imx);
-
/* read/write data */
for (i = 0; i < num; i++) {
if (i) {
@@ -386,6 +415,9 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
temp = readb(i2c_imx->base + IMX_I2C_I2CR);
temp |= I2CR_RSTA;
writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+ result = i2c_imx_bus_busy(i2c_imx, 1);
+ if (result)
+ goto fail0;
}
dev_dbg(&i2c_imx->adapter.dev,
"<%s> transfer message: %d\n", __func__, i);
@@ -500,7 +532,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
dev_err(&pdev->dev, "can't get I2C clock\n");
goto fail3;
}
- clk_enable(i2c_imx->clk);
/* Request IRQ */
ret = request_irq(i2c_imx->irq, i2c_imx_isr, 0, pdev->name, i2c_imx);
@@ -549,7 +580,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
fail5:
free_irq(i2c_imx->irq, i2c_imx);
fail4:
- clk_disable(i2c_imx->clk);
clk_put(i2c_imx->clk);
fail3:
release_mem_region(i2c_imx->res->start, resource_size(res));
@@ -586,8 +616,6 @@ static int __exit i2c_imx_remove(struct platform_device *pdev)
if (pdata && pdata->exit)
pdata->exit(&pdev->dev);
- /* Disable I2C clock */
- clk_disable(i2c_imx->clk);
clk_put(i2c_imx->clk);
release_mem_region(i2c_imx->res->start, resource_size(i2c_imx->res));
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index d325e86e3103..f627001108b8 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -365,9 +365,6 @@ static int mpc_write(struct mpc_i2c *i2c, int target,
unsigned timeout = i2c->adap.timeout;
u32 flags = restart ? CCR_RSTA : 0;
- /* Start with MEN */
- if (!restart)
- writeccr(i2c, CCR_MEN);
/* Start as master */
writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_MTX | flags);
/* Write target byte */
@@ -396,9 +393,6 @@ static int mpc_read(struct mpc_i2c *i2c, int target,
int i, result;
u32 flags = restart ? CCR_RSTA : 0;
- /* Start with MEN */
- if (!restart)
- writeccr(i2c, CCR_MEN);
/* Switch to read - restart */
writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_MTX | flags);
/* Write target address byte - this time with the read flag set */
@@ -425,9 +419,9 @@ static int mpc_read(struct mpc_i2c *i2c, int target,
/* Generate txack on next to last byte */
if (i == length - 2)
writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_TXAK);
- /* Generate stop on last byte */
+ /* Do not generate stop on last byte */
if (i == length - 1)
- writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_TXAK);
+ writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_MTX);
data[i] = readb(i2c->base + MPC_I2C_DR);
}