2022-09-21 11:24:21

by chenweilong

Subject: [PATCH] i2c: hisi: Add support to get clock frequency from clock property

Support the driver to obtain clock information by clk_rate or
clock property. Find clock first, if not, fall back to clk_rate.

Signed-off-by: Weilong Chen <[email protected]>
---
drivers/i2c/busses/i2c-hisi.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-hisi.c b/drivers/i2c/busses/i2c-hisi.c
index 67031024217c..5e48d4ee0c6d 100644
--- a/drivers/i2c/busses/i2c-hisi.c
+++ b/drivers/i2c/busses/i2c-hisi.c
@@ -8,6 +8,7 @@
#include <linux/acpi.h>
#include <linux/bits.h>
#include <linux/bitfield.h>
+#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
@@ -91,6 +92,7 @@ struct hisi_i2c_controller {
void __iomem *iobase;
struct device *dev;
int irq;
+ struct clk *clk;

/* Intermediates for recording the transfer process */
struct completion *completion;
@@ -456,10 +458,21 @@ static int hisi_i2c_probe(struct platform_device *pdev)
return ret;
}

- ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
- if (ret) {
- dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
- return ret;
+ ctlr->clk = devm_clk_get_optional(&pdev->dev, NULL);
+ if (IS_ERR(ctlr->clk)) {
+ ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
+ if (ret) {
+ dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
+ return ret;
+ }
+ } else {
+ ret = clk_prepare_enable(ctlr->clk);
+ if (ret) {
+ dev_err(dev, "failed to enable clock, ret = %d\n", ret);
+ return ret;
+ }
+
+ clk_rate_hz = clk_get_rate(ctlr->clk);
}

ctlr->clk_rate_khz = DIV_ROUND_UP_ULL(clk_rate_hz, HZ_PER_KHZ);
@@ -475,8 +488,10 @@ static int hisi_i2c_probe(struct platform_device *pdev)
i2c_set_adapdata(adapter, ctlr);

ret = devm_i2c_add_adapter(dev, adapter);
- if (ret)
+ if (ret) {
+ clk_disable_unprepare(ctlr->clk);
return ret;
+ }

hw_version = readl(ctlr->iobase + HISI_I2C_VERSION);
dev_info(ctlr->dev, "speed mode is %s. hw version 0x%x\n",
--
2.31.GIT

2022-09-22 12:14:24

by Yicong Yang

Subject: Re: [PATCH] i2c: hisi: Add support to get clock frequency from clock property

Hi Weilong,

On 2022/9/21 18:15, Weilong Chen wrote:
> Support the driver to obtain clock information by clk_rate or
> clock property. Find clock first, if not, fall back to clk_rate.
>
> Signed-off-by: Weilong Chen <[email protected]>
> ---
> drivers/i2c/busses/i2c-hisi.c | 25 ++++++++++++++++++++-----
> 1 file changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-hisi.c b/drivers/i2c/busses/i2c-hisi.c
> index 67031024217c..5e48d4ee0c6d 100644
> --- a/drivers/i2c/busses/i2c-hisi.c
> +++ b/drivers/i2c/busses/i2c-hisi.c
> @@ -8,6 +8,7 @@
> #include <linux/acpi.h>
> #include <linux/bits.h>
> #include <linux/bitfield.h>
> +#include <linux/clk.h>
> #include <linux/completion.h>
> #include <linux/i2c.h>
> #include <linux/interrupt.h>
> @@ -91,6 +92,7 @@ struct hisi_i2c_controller {
> void __iomem *iobase;
> struct device *dev;
> int irq;
> + struct clk *clk;
>

Prefer to make this field between @irq and @dev, to make these fields ordered
in an inverted triangle.

> /* Intermediates for recording the transfer process */
> struct completion *completion;
> @@ -456,10 +458,21 @@ static int hisi_i2c_probe(struct platform_device *pdev)
> return ret;
> }
>
> - ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
> - if (ret) {
> - dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
> - return ret;
> + ctlr->clk = devm_clk_get_optional(&pdev->dev, NULL);
> + if (IS_ERR(ctlr->clk)) {

Use IS_ERR_OR_NULL(), otherwise we cannot get the clock rate.

> + ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
> + if (ret) {
> + dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
> + return ret;
> + }
> + } else {
> + ret = clk_prepare_enable(ctlr->clk);

You didn't disable and unprepare the clock on removal.

Use devm_clk_get_optional_enabled() instead then it's managed by devres and the error path
below is unnecessary as well.

BTW, do we really need to prepare and enable the clock? I checked designware-i2c seems it only
gets the clock rate and don't do the prepare and enable operations. I may miss something but
please have a check.

Thanks,
Yicong

> + if (ret) {
> + dev_err(dev, "failed to enable clock, ret = %d\n", ret);
> + return ret;
> + }
> +
> + clk_rate_hz = clk_get_rate(ctlr->clk);
> }
>
> ctlr->clk_rate_khz = DIV_ROUND_UP_ULL(clk_rate_hz, HZ_PER_KHZ);
> @@ -475,8 +488,10 @@ static int hisi_i2c_probe(struct platform_device *pdev)
> i2c_set_adapdata(adapter, ctlr);
>
> ret = devm_i2c_add_adapter(dev, adapter);
> - if (ret)
> + if (ret) {
> + clk_disable_unprepare(ctlr->clk);
> return ret;
> + }
>
> hw_version = readl(ctlr->iobase + HISI_I2C_VERSION);
> dev_info(ctlr->dev, "speed mode is %s. hw version 0x%x\n",
>