From 6c403594354d59fb288978c5a23008da89ba2741 Mon Sep 17 00:00:00 2001
From: Jonas Karlman <jonas@kwiboo.se>
Date: Fri, 27 Mar 2026 13:17:48 +0000
Subject: [PATCH] nvmem: rockchip-otp: Handle internal word_size in main
 reg_read op

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>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>
Link: https://patch.msgid.link/20260327131751.3026030-7-srini@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/nvmem/rockchip-otp.c | 72 ++++++++++++++++++++----------------
 1 file changed, 40 insertions(+), 32 deletions(-)

--- 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 @@ read_end:
 }
 
 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 *conte
 			     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 *conte
 		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_d
 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_clo
 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,
