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Subject[PATCH 4.9 09/16] i2c: imx: use clk notifier for rate changes
Date
From: Lucas Stach <l.stach@pengutronix.de>

commit 90ad2cbe88c22d0215225ab9594eeead0eb24fde upstream

Instead of repeatedly calling clk_get_rate for each transfer, register
a clock notifier to update the cached divider value each time the clock
rate actually changes.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/i2c/busses/i2c-imx.c | 32 +++++++++++++++++++++++++-------
1 file changed, 25 insertions(+), 7 deletions(-)

--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -194,6 +194,7 @@ struct imx_i2c_dma {
struct imx_i2c_struct {
struct i2c_adapter adapter;
struct clk *clk;
+ struct notifier_block clk_change_nb;
void __iomem *base;
wait_queue_head_t queue;
unsigned long i2csr;
@@ -468,15 +469,14 @@ static int i2c_imx_acked(struct imx_i2c_
return 0;
}

-static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx)
+static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
+ unsigned int i2c_clk_rate)
{
struct imx_i2c_clk_pair *i2c_clk_div = i2c_imx->hwdata->clk_div;
- unsigned int i2c_clk_rate;
unsigned int div;
int i;

/* Divider value calculation */
- i2c_clk_rate = clk_get_rate(i2c_imx->clk);
if (i2c_imx->cur_clk == i2c_clk_rate)
return;

@@ -511,6 +511,20 @@ static void i2c_imx_set_clk(struct imx_i
#endif
}

+static int i2c_imx_clk_notifier_call(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct clk_notifier_data *ndata = data;
+ struct imx_i2c_struct *i2c_imx = container_of(&ndata->clk,
+ struct imx_i2c_struct,
+ clk);
+
+ if (action & POST_RATE_CHANGE)
+ i2c_imx_set_clk(i2c_imx, ndata->new_rate);
+
+ return NOTIFY_OK;
+}
+
static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
{
unsigned int temp = 0;
@@ -518,8 +532,6 @@ static int i2c_imx_start(struct imx_i2c_

dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);

- i2c_imx_set_clk(i2c_imx);
-
imx_i2c_write_reg(i2c_imx->ifdr, i2c_imx, IMX_I2C_IFDR);
/* Enable I2C controller */
imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
@@ -1131,6 +1143,9 @@ static int i2c_imx_probe(struct platform
"clock-frequency", &i2c_imx->bitrate);
if (ret < 0 && pdata && pdata->bitrate)
i2c_imx->bitrate = pdata->bitrate;
+ i2c_imx->clk_change_nb.notifier_call = i2c_imx_clk_notifier_call;
+ clk_notifier_register(i2c_imx->clk, &i2c_imx->clk_change_nb);
+ i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));

/* Set up chip registers to defaults */
imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN,
@@ -1141,12 +1156,12 @@ static int i2c_imx_probe(struct platform
ret = i2c_imx_init_recovery_info(i2c_imx, pdev);
/* Give it another chance if pinctrl used is not ready yet */
if (ret == -EPROBE_DEFER)
- goto rpm_disable;
+ goto clk_notifier_unregister;

/* Add I2C adapter */
ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
if (ret < 0)
- goto rpm_disable;
+ goto clk_notifier_unregister;

pm_runtime_mark_last_busy(&pdev->dev);
pm_runtime_put_autosuspend(&pdev->dev);
@@ -1162,6 +1177,8 @@ static int i2c_imx_probe(struct platform

return 0; /* Return OK */

+clk_notifier_unregister:
+ clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb);
rpm_disable:
pm_runtime_put_noidle(&pdev->dev);
pm_runtime_disable(&pdev->dev);
@@ -1195,6 +1212,7 @@ static int i2c_imx_remove(struct platfor
imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR);
imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);

+ clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb);
clk_disable_unprepare(i2c_imx->clk);

pm_runtime_put_noidle(&pdev->dev);

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