Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: 8hHQjyDTpQPYyRaQ7+P8+tOPLeHWDA725TEnzf4iJBQkNT2tVdKwuLgLTb7NXcQZy71Clnd8IA
 z2zbUzZfNLqw==
IronPort-SDR: 2bLyo6B1Uhjbr/+687E9timHVVbn1zeuvQckrYhKMQTXMj/8gqmF2jPUeOypLs2+yf0LgYR84F
 dEU+btICSAZg==
Date:   Mon, 15 Jun 2020 12:29:23 +0300
From:   Sakari Ailus <sakari.ailus@linux.intel.com>
To:     Bingbu Cao <bingbu.cao@intel.com>
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        srinivas.kandagatla@linaro.org, tfiga@chromium.org,
        bingbu.cao@linux.intel.com
Subject: Re: [PATCH] media: ov2740: add NVMEM interface to read customized
 OTP data
Message-ID: <20200615092923.GT16711@paasikivi.fi.intel.com>
References: <1591954922-14006-1-git-send-email-bingbu.cao@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1591954922-14006-1-git-send-email-bingbu.cao@intel.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Bingbu,

Thank you for the patch.

On Fri, Jun 12, 2020 at 05:42:02PM +0800, Bingbu Cao wrote:
> From: Qingwu Zhang <qingwu.zhang@intel.com>
> 
> ov2740 includes 512bytes of one-time programmable memory and
> 256 bytes are reserved for customers which can be used to store
> customized information. This patch provide an NVMEM interface
> to support read out the customized data in OTP.
> 
> Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
> Signed-off-by: Qingwu Zhang <qingwu.zhang@intel.com>
> ---
>  drivers/media/i2c/ov2740.c | 145 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 145 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c
> index 33025c6d23ac..fd0b6a903ec1 100644
> --- a/drivers/media/i2c/ov2740.c
> +++ b/drivers/media/i2c/ov2740.c
> @@ -7,6 +7,8 @@
>  #include <linux/i2c.h>
>  #include <linux/module.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/nvmem-provider.h>
> +#include <linux/regmap.h>
>  #include <media/v4l2-ctrls.h>
>  #include <media/v4l2-device.h>
>  #include <media/v4l2-fwnode.h>
> @@ -59,6 +61,21 @@
>  #define OV2740_TEST_PATTERN_ENABLE	BIT(7)
>  #define OV2740_TEST_PATTERN_BAR_SHIFT	2
>  
> +/* ISP CTRL00 */
> +#define OV2740_REG_ISP_CTRL00		0x5000
> +/* ISP CTRL01 */
> +#define OV2740_REG_ISP_CTRL01		0x5001
> +/* Customer Addresses: 0x7010 - 0x710F */
> +#define CUSTOMER_USE_OTP_SIZE		0x100
> +/* OTP registers from sensor */
> +#define OV2740_REG_OTP_CUSTOMER		0x7010
> +
> +struct nvm_data {
> +	char *nvm_buffer;
> +	struct nvmem_device *nvmem;
> +	struct regmap *regmap;
> +};
> +
>  enum {
>  	OV2740_LINK_FREQ_360MHZ_INDEX,
>  };
> @@ -915,6 +932,130 @@ static int ov2740_remove(struct i2c_client *client)
>  	return 0;
>  }
>  
> +static int ov2740_load_otp_data(struct i2c_client *client, struct nvm_data *nvm)
> +{
> +	struct ov2740 *ov2740 = to_ov2740(i2c_get_clientdata(client));
> +	u32 isp_ctrl00 = 0;
> +	u32 isp_ctrl01 = 0;
> +	int ret;
> +
> +	ret = ov2740_read_reg(ov2740, OV2740_REG_ISP_CTRL00, 1, &isp_ctrl00);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to read ISP CTRL00\n");
> +		goto exit;
> +	}
> +	ret = ov2740_read_reg(ov2740, OV2740_REG_ISP_CTRL01, 1, &isp_ctrl01);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to read ISP CTRL01\n");
> +		goto exit;
> +	}
> +
> +	/* Clear bit 5 of ISP CTRL00 */
> +	ret = ov2740_write_reg(ov2740, OV2740_REG_ISP_CTRL00, 1,
> +			       isp_ctrl00 & ~BIT(5));
> +	if (ret) {
> +		dev_err(&client->dev, "failed to write ISP CTRL00\n");
> +		goto exit;
> +	}
> +
> +	/* Clear bit 7 of ISP CTRL01 */
> +	ret = ov2740_write_reg(ov2740, OV2740_REG_ISP_CTRL01, 1,
> +			       isp_ctrl01 & ~BIT(7));
> +	if (ret) {
> +		dev_err(&client->dev, "failed to write ISP CTRL01\n");
> +		goto exit;
> +	}
> +
> +	ret = ov2740_write_reg(ov2740, OV2740_REG_MODE_SELECT, 1,
> +			       OV2740_MODE_STREAMING);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to start streaming\n");
> +		goto exit;
> +	}
> +
> +	/*
> +	 * Users are not allowed to access OTP-related registers and memory
> +	 * during the 20 ms period after streaming starts (0x100 = 0x01).
> +	 */
> +	msleep(20);
> +
> +	ret = regmap_bulk_read(nvm->regmap, OV2740_REG_OTP_CUSTOMER,
> +			       nvm->nvm_buffer, CUSTOMER_USE_OTP_SIZE);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to read OTP data, ret %d\n", ret);
> +		goto exit;
> +	}
> +
> +	ov2740_write_reg(ov2740, OV2740_REG_MODE_SELECT, 1,
> +			 OV2740_MODE_STANDBY);
> +	ov2740_write_reg(ov2740, OV2740_REG_ISP_CTRL01, 1, isp_ctrl01);
> +	ov2740_write_reg(ov2740, OV2740_REG_ISP_CTRL00, 1, isp_ctrl00);
> +
> +exit:
> +	return ret;
> +}
> +
> +static int ov2740_nvmem_read(void *priv, unsigned int off, void *val,
> +			     size_t count)
> +{
> +	struct nvm_data *nvm = priv;
> +
> +	memcpy(val, nvm->nvm_buffer + off, count);
> +
> +	return 0;
> +}
> +
> +static int ov2740_register_nvmem(struct i2c_client *client)
> +{
> +	struct nvm_data *nvm;
> +	struct regmap_config regmap_config = { };
> +	struct nvmem_config nvmem_config = { };
> +	struct regmap *regmap;
> +	struct device *dev = &client->dev;
> +	int ret = 0;
> +
> +	nvm = devm_kzalloc(dev, sizeof(*nvm), GFP_KERNEL);
> +	if (!nvm)
> +		return -ENOMEM;
> +
> +	regmap_config.val_bits = 8;
> +	regmap_config.reg_bits = 16;
> +	regmap_config.disable_locking = true;
> +	regmap = devm_regmap_init_i2c(client, &regmap_config);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	nvm->regmap = regmap;
> +
> +	nvmem_config.name = dev_name(dev);
> +	nvmem_config.dev = dev;
> +	nvmem_config.read_only = true;
> +	nvmem_config.root_only = true;
> +	nvmem_config.owner = THIS_MODULE;
> +	nvmem_config.compat = true;
> +	nvmem_config.base_dev = dev;
> +	nvmem_config.reg_read = ov2740_nvmem_read;
> +	nvmem_config.reg_write = NULL;
> +	nvmem_config.priv = nvm;
> +	nvmem_config.stride = 1;
> +	nvmem_config.word_size = 1;
> +	nvmem_config.size = CUSTOMER_USE_OTP_SIZE;
> +
> +	nvm->nvmem = devm_nvmem_register(dev, &nvmem_config);
> +	if (IS_ERR(nvm->nvmem))
> +		return PTR_ERR(nvm->nvmem);
> +
> +	nvm->nvm_buffer = devm_kzalloc(dev, CUSTOMER_USE_OTP_SIZE, GFP_KERNEL);
> +	if (!nvm->nvm_buffer)
> +		return -ENOMEM;
> +
> +	ret = ov2740_load_otp_data(client, nvm);
> +	if (ret)
> +		dev_err(dev, "failed to load OTP data, ret %d\n", ret);
> +
> +	return ret;
> +}
> +
>  static int ov2740_probe(struct i2c_client *client)
>  {
>  	struct ov2740 *ov2740;
> @@ -964,6 +1105,10 @@ static int ov2740_probe(struct i2c_client *client)
>  		goto probe_error_media_entity_cleanup;
>  	}
>  
> +	ret = ov2740_register_nvmem(client);
> +	if (ret)
> +		dev_err(&client->dev, "register nvmem failed, ret %d\n", ret);
> +
>  	/*
>  	 * Device is already turned on by i2c-core with ACPI domain PM.
>  	 * Enable runtime PM and turn off the device.

Could you add #ifdefs for CONFIG_NVMEM so this compiles when it's disabled?
It's bool so a simple #ifdef will do. I think ov2740_register_nvmem() could
have a dummy implementation so this wouldn't litter the probe function.

Thanks.

-- 
Kind regards,

Sakari Ailus