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Merge branch 'i2c-fixes' of git://git.fluff.org/bjdooks/linux
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* '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
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Linus Torvalds committed Nov 3, 2009
2 parents 1cec2cd + 45da790 commit 78e1e34
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Showing 2 changed files with 59 additions and 37 deletions.
86 changes: 57 additions & 29 deletions drivers/i2c/busses/i2c-imx.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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__);
Expand Down Expand Up @@ -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,
Expand All @@ -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.
Expand Down Expand Up @@ -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__);
Expand All @@ -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) {
Expand All @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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));
Expand Down Expand Up @@ -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));
Expand Down
10 changes: 2 additions & 8 deletions drivers/i2c/busses/i2c-mpc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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 */
Expand All @@ -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);
}

Expand Down

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