Re: [PATCH] media: ov2740: add NVMEM interface to read customized OTP data
From: Sakari Ailus
Date: Mon Jun 15 2020 - 05:29:59 EST
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@xxxxxxxxx>
>
> 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@xxxxxxxxx>
> Signed-off-by: Qingwu Zhang <qingwu.zhang@xxxxxxxxx>
> ---
> 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, ®map_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