[PATCH 4/4] i2c: imx: disable clock when it's possible to save power.

Richard Zhao
2009-09-30T05:55:06Z

Enable clock before START, disable it after STOP.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 87faea4..72ddea3 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -120,6 +120,7 @@ struct imx_i2c_struct {
wait_queue_head_t queue;
unsigned long i2csr;
unsigned int disable_delay;
+ unsigned int ifdr; /* IMX_I2C_IFDR */
};

/** Functions for IMX I2C adapter driver ***************************************
@@ -210,6 +211,8 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)

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);
@@ -254,6 +257,7 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)

/* 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,
@@ -273,8 +277,8 @@ 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];

if (cpu_is_mx1()) {
/*
@@ -555,7 +559,6 @@ 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);
@@ -604,7 +607,6 @@ 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));
@@ -641,8 +643,6 @@ 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));
--
1.6.0.4