Re: [PATCH] nvmem: rockchip-otp: Handle internal word_size in main reg_read op

["Heiko Stübner" <heiko@sntech.de>]

Am Sonntag, 16. März 2025, 20:18:58 Mitteleuropäische Sommerzeit schrieb Jonas Karlman:
> Rockchip SoCs RK3576 and RK3588 read data from the OTP using 32-bit
> words instead of normal 8-bit bytes. Similar RK3506, RK3528, RK3562 and
> RK3568 will read data from OTP using 16-bit words.
> 
> The nvmem core stride and word_size cannot fully be used as cells is not
> always aligned. Continue to report a stride=1 and word_size=1 in
> nvmem_config and instead handle use of SoC specific word_size internally
> in the driver.
> 
> Move current SoC specific word_size handling from the RK3588 read_reg
> operation to the main read_reg operation to help simplify the SoC
> specific read_reg operation and allow code reuse in a future RK3568
> reg_read operation.
> 
> Signed-off-by: Jonas Karlman <jonas@kwiboo.se>

Reviewed-by: Heiko Stuebner <heiko@sntech.de>

On both rk3576 and rk3588 compared nvmem content before and after
the change, so

Tested-by: Heiko Stuebner <heiko@sntech.de>


> ---
> This closely matches how I refactored the Rockchip eFUSE and OTP driver
> in mainline U-Boot to handle word/block reads back in 2023, see [1].
> 
> [1] http://lore.kernel.org/r/20230222224436.1570224-3-jonas@kwiboo.se/
> ---
>  drivers/nvmem/rockchip-otp.c | 72 ++++++++++++++++++++----------------
>  1 file changed, 40 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/nvmem/rockchip-otp.c b/drivers/nvmem/rockchip-otp.c
> index d88f12c53242..45bbb6147fb7 100644
> --- a/drivers/nvmem/rockchip-otp.c
> +++ b/drivers/nvmem/rockchip-otp.c
> @@ -59,7 +59,6 @@
>  #define RK3588_OTPC_AUTO_EN		0x08
>  #define RK3588_OTPC_INT_ST		0x84
>  #define RK3588_OTPC_DOUT0		0x20
> -#define RK3588_NBYTES			4
>  #define RK3588_BURST_NUM		1
>  #define RK3588_BURST_SHIFT		8
>  #define RK3588_ADDR_SHIFT		16
> @@ -69,6 +68,7 @@
>  struct rockchip_data {
>  	int size;
>  	int read_offset;
> +	int word_size;
>  	const char * const *clks;
>  	int num_clks;
>  	nvmem_reg_read_t reg_read;
> @@ -185,48 +185,28 @@ static int px30_otp_read(void *context, unsigned int offset,
>  }
>  
>  static int rk3588_otp_read(void *context, unsigned int offset,
> -			   void *val, size_t bytes)
> +			   void *val, size_t count)
>  {
>  	struct rockchip_otp *otp = context;
> -	unsigned int addr_start, addr_end, addr_len;
> -	int ret, i = 0;
> -	u32 data;
> -	u8 *buf;
> -
> -	addr_start = round_down(offset, RK3588_NBYTES) / RK3588_NBYTES;
> -	addr_end = round_up(offset + bytes, RK3588_NBYTES) / RK3588_NBYTES;
> -	addr_len = addr_end - addr_start;
> -	addr_start += otp->data->read_offset / RK3588_NBYTES;
> -
> -	buf = kzalloc(array_size(addr_len, RK3588_NBYTES), GFP_KERNEL);
> -	if (!buf)
> -		return -ENOMEM;
> +	u32 *buf = val;
> +	int ret;
>  
> -	while (addr_len--) {
> -		writel((addr_start << RK3588_ADDR_SHIFT) |
> +	while (count--) {
> +		writel((offset++ << RK3588_ADDR_SHIFT) |
>  		       (RK3588_BURST_NUM << RK3588_BURST_SHIFT),
>  		       otp->base + RK3588_OTPC_AUTO_CTRL);
>  		writel(RK3588_AUTO_EN, otp->base + RK3588_OTPC_AUTO_EN);
>  
>  		ret = rockchip_otp_wait_status(otp, RK3588_OTPC_INT_ST,
>  					       RK3588_RD_DONE);
> -		if (ret < 0) {
> +		if (ret) {
>  			dev_err(otp->dev, "timeout during read setup\n");
> -			goto read_end;
> +			return ret;
>  		}
>  
> -		data = readl(otp->base + RK3588_OTPC_DOUT0);
> -		memcpy(&buf[i], &data, RK3588_NBYTES);
> -
> -		i += RK3588_NBYTES;
> -		addr_start++;
> +		*buf++ = readl(otp->base + RK3588_OTPC_DOUT0);
>  	}
>  
> -	memcpy(val, buf + offset % RK3588_NBYTES, bytes);
> -
> -read_end:
> -	kfree(buf);
> -
>  	return ret;
>  }
>  
> @@ -234,7 +214,7 @@ static int rockchip_otp_read(void *context, unsigned int offset,
>  			     void *val, size_t bytes)
>  {
>  	struct rockchip_otp *otp = context;
> -	int ret;
> +	int ret, word_size;
>  
>  	if (!otp->data || !otp->data->reg_read)
>  		return -EINVAL;
> @@ -245,8 +225,34 @@ static int rockchip_otp_read(void *context, unsigned int offset,
>  		return ret;
>  	}
>  
> -	ret = otp->data->reg_read(context, offset, val, bytes);
> +	offset += otp->data->read_offset;
> +	word_size = otp->data->word_size;
> +
> +	if (word_size > 1) {
> +		unsigned int addr_start, addr_end;
> +		size_t count;
> +		u8 *buf;
> +
> +		addr_start = offset / word_size;
> +		addr_end = DIV_ROUND_UP(offset + bytes, word_size);
> +		count = addr_end - addr_start;
> +
> +		buf = kzalloc(array_size(count, word_size), GFP_KERNEL);
> +		if (!buf) {
> +			ret = -ENOMEM;
> +			goto err;
> +		}
> +
> +		ret = otp->data->reg_read(context, addr_start, buf, count);
> +		if (!ret)
> +			memcpy(val, buf + (offset % word_size), bytes);
> +
> +		kfree(buf);
> +	} else {
> +		ret = otp->data->reg_read(context, offset, val, bytes);
> +	}
>  
> +err:
>  	clk_bulk_disable_unprepare(otp->data->num_clks, otp->clks);
>  
>  	return ret;
> @@ -259,7 +265,7 @@ static struct nvmem_config otp_config = {
>  	.type = NVMEM_TYPE_OTP,
>  	.read_only = true,
>  	.stride = 1,
> -	.word_size = 1,
> +	.word_size = sizeof(u8),
>  	.reg_read = rockchip_otp_read,
>  };
>  
> @@ -277,6 +283,7 @@ static const struct rockchip_data px30_data = {
>  static const struct rockchip_data rk3576_data = {
>  	.size = 0x100,
>  	.read_offset = 0x700,
> +	.word_size = sizeof(u32),
>  	.clks = px30_otp_clocks,
>  	.num_clks = ARRAY_SIZE(px30_otp_clocks),
>  	.reg_read = rk3588_otp_read,
> @@ -289,6 +296,7 @@ static const char * const rk3588_otp_clocks[] = {
>  static const struct rockchip_data rk3588_data = {
>  	.size = 0x400,
>  	.read_offset = 0xc00,
> +	.word_size = sizeof(u32),
>  	.clks = rk3588_otp_clocks,
>  	.num_clks = ARRAY_SIZE(rk3588_otp_clocks),
>  	.reg_read = rk3588_otp_read,
>