Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1382261 > unrolled thread

[PATCH 3/3] nvmem: imx-ocotp: handling clock

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH 3/3] nvmem: imx-ocotp: handling clock Peng Fan <van.freenix@gmail.com> - 2016-04-19 10:20 +0200
    Re: [PATCH 3/3] nvmem: imx-ocotp: handling clock Fabio Estevam <festevam@gmail.com> - 2016-04-19 12:50 +0200
      Re: [PATCH 3/3] nvmem: imx-ocotp: handling clock Peng Fan <van.freenix@gmail.com> - 2016-04-19 15:30 +0200

#1382261 — [PATCH 3/3] nvmem: imx-ocotp: handling clock

Before access ocotp nvmem area, the clock should be enabled.
Or, `hexdump nvmem` will hang the system. So, use such flow:
"
  1. clock_enable_prepare
  2. read nvmem ocotp area
  3. clock_disable_unprepare
"

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Shawn Guo <shawnguo@kernel.org>
---
 drivers/nvmem/imx-ocotp.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
index d7796eb..55095c0 100644
--- a/drivers/nvmem/imx-ocotp.c
+++ b/drivers/nvmem/imx-ocotp.c
@@ -15,6 +15,7 @@
  * http://www.gnu.org/copyleft/gpl.html
  */
 
+#include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/module.h>
@@ -27,6 +28,7 @@
 
 struct ocotp_priv {
 	struct device *dev;
+	struct clk *clk;
 	void __iomem *base;
 	unsigned int nregs;
 };
@@ -46,11 +48,15 @@ static int imx_ocotp_read(void *context, const void *reg, size_t reg_size,
 	if (count > (priv->nregs - index))
 		count = priv->nregs - index;
 
+	clk_prepare_enable(priv->clk);
+
 	for (i = index; i < (index + count); i++) {
 		*(u32 *)val = readl(priv->base + 0x400 + i * 0x10);
 		val += 4;
 	}
 
+	clk_disable_unprepare(priv->clk);
+
 	return 0;
 }
 
@@ -112,6 +118,10 @@ static int imx_ocotp_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);
 
+	priv->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->clk))
+		return PTR_ERR(priv->clk);
+
 	of_id = of_match_device(imx_ocotp_dt_ids, dev);
 	priv->nregs = (unsigned int)of_id->data;
 	imx_ocotp_regmap_config.max_register = 4 * priv->nregs - 4;
-- 
1.8.4.5

[toc] | [next] | [standalone]

#1382387

Hi Peng,

On Tue, Apr 19, 2016 at 5:33 AM, Peng Fan <van.freenix@gmail.com> wrote:

> @@ -46,11 +48,15 @@ static int imx_ocotp_read(void *context, const void *reg, size_t reg_size,
>         if (count > (priv->nregs - index))
>                 count = priv->nregs - index;
>
> +       clk_prepare_enable(priv->clk);

clk_prepare_enable() may fail, so you should better check its return
value and propagate it in the case of error.

[toc] | [prev] | [next] | [standalone]

#1382514

Hi Fabio,
On Tue, Apr 19, 2016 at 07:42:17AM -0300, Fabio Estevam wrote:
>Hi Peng,
>
>On Tue, Apr 19, 2016 at 5:33 AM, Peng Fan <van.freenix@gmail.com> wrote:
>
>> @@ -46,11 +48,15 @@ static int imx_ocotp_read(void *context, const void *reg, size_t reg_size,
>>         if (count > (priv->nregs - index))
>>                 count = priv->nregs - index;
>>
>> +       clk_prepare_enable(priv->clk);
>
>clk_prepare_enable() may fail, so you should better check its return
>value and propagate it in the case of error.

Thanks for correcting me. Will fix it in V2.

Thanks,
Peng

-- 

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web