Am Freitag, 31. Januar 2025, 17:06:23 CET schrieb Frank Li:

On Fri, Jan 31, 2025 at 02:54:06PM +0100, Alexander Stein wrote:

quoted

Hi,

Am Donnerstag, 30. Januar 2025, 17:42:32 CET schrieb Frank Li:

quoted

On Thu, Jan 30, 2025 at 02:01:00PM +0100, Alexander Stein wrote:

quoted

i.MX8M OCOTP supports a specific peripheral or function being fused
which means disabled, so
 - Introduce disable_fuse for a list of possible fused peripherals.
 - Iterate all nodes to check accessing permission. If not
   allowed to be accessed, detach the node

Signed-off-by: Alexander Stein <redacted>
---
 drivers/nvmem/Kconfig     |   3 ++
 drivers/nvmem/imx-ocotp.c | 105 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 107 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 8671b7c974b93..ba5c928cab520 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig

@@ -84,6 +84,9 @@ config NVMEM_IMX_OCOTP
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem-imx-ocotp.

+	  If built as modules, any other driver relying on this working
+	  as access controller also needs to be a module as well.
+
 config NVMEM_IMX_OCOTP_ELE
 	tristate "i.MX On-Chip OTP Controller support"
 	depends on ARCH_MXC || COMPILE_TEST

diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
index c5086a16450ac..e3ea026a37d0d 100644
--- a/drivers/nvmem/imx-ocotp.c
+++ b/drivers/nvmem/imx-ocotp.c

@@ -23,6 +23,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <dt-bindings/nvmem/fsl,imx8mn-ocotp.h>

 #define IMX_OCOTP_OFFSET_B0W0		0x400 /* Offset from base address of the
 					       * OTP Bank0 Word0

@@ -91,11 +92,20 @@ struct ocotp_ctrl_reg {
 	u32 bm_rel_shadows;
 };

+#define OCOTP_MAX_NUM_GATE_WORDS 4
+
+struct disable_fuse {
+	u32 fuse_addr;
+	u32 mask;
+};
+
 struct ocotp_params {
 	unsigned int nregs;
 	unsigned int bank_address_words;
 	void (*set_timing)(struct ocotp_priv *priv);
 	struct ocotp_ctrl_reg ctrl;
+	u32 num_disables;
+	struct disable_fuse *disables;
 };

 static int imx_ocotp_wait_for_busy(struct ocotp_priv *priv, u32 flags)

@@ -552,11 +562,25 @@ static const struct ocotp_params imx8mm_params = {
 	.ctrl = IMX_OCOTP_BM_CTRL_DEFAULT,
 };

+struct disable_fuse imx8mn_disable_fuse[] = {
+		[IMX8MN_OCOTP_M7_DISABLE]	= { .fuse_addr = 20, .mask = BIT(8) },
+		[IMX8MN_OCOTP_M7_MPU_DISABLE]	= { .fuse_addr = 20, .mask = BIT(9) },
+		[IMX8MN_OCOTP_M7_FPU_DISABLE]	= { .fuse_addr = 20, .mask = BIT(10) },
+		[IMX8MN_OCOTP_USB_OTG1_DISABLE]	= { .fuse_addr = 20, .mask = BIT(11) },
+		[IMX8MN_OCOTP_GPU3D_DISABLE]	= { .fuse_addr = 20, .mask = BIT(24) },
+		[IMX8MN_OCOTP_MIPI_DSI_DISABLE]	= { .fuse_addr = 20, .mask = BIT(28) },
+		[IMX8MN_OCOTP_ENET_DISABLE]	= { .fuse_addr = 20, .mask = BIT(29) },
+		[IMX8MN_OCOTP_MIPI_CSI_DISABLE]	= { .fuse_addr = 20, .mask = BIT(30) },
+		[IMX8MN_OCOTP_ASRC_DISABLE]	= { .fuse_addr = 20, .mask = BIT(31) },
+};

Can we direct define IMX8MN_OCOTP_M7_DISABLE as BIT(8), so avoid this
map data?

This would be possible for imx8mn, but not for imx8mp which uses
multiples fuses for disables. This is an excerpt from imx8mp WIP

quoted

struct disable_fuse imx8mp_disable_fuse[] = {
	[IMX8MP_OCOTP_CAN_DISABLE]		= { .fuse_addr = 16, .mask = BIT(28) },
	[IMX8MP_OCOTP_CAN_FD_DISABLE]		= { .fuse_addr = 16, .mask = BIT(29) },
	[IMX8MP_OCOTP_VPU_VC8000E_DISABLE]	= { .fuse_addr = 16, .mask = BIT(30) },
	[IMX8MP_OCOTP_IMG_ISP1_DISABLE]		= { .fuse_addr = 20, .mask = BIT(0) },
	[IMX8MP_OCOTP_IMG_ISP2_DISABLE]		= { .fuse_addr = 20, .mask = BIT(1) },
	[IMX8MP_OCOTP_IMG_DEWARP_DISABLE]	= { .fuse_addr = 20, .mask = BIT(2) },
};

Notice the fuse_addr of 16 and 20.

Yes, I am not sure if it good idea to encode fuse_addr to IMX8MP_OCOTP_CAN_DISABLE

like

#define IMX8MP_OCOTP_CAN_DISABLE  16 << 16 | BIT(28)

So dt-bindings/nvmem/fsl,imx8mn-ocotp.h can be moved to dts directory.

Mh, I personally don't like encoding offsets into bits. How about using

'#access-controller-cells = <2>'

and using the defines like this

#define IMX8MP_OCOTP_CAN_DISABLE  16 0x10000000

DT stays the same:

access-controllers = <&ocotp IMX8MP_OCOTP_CAN_DISABLE>;

Note: It seems BIT(x) is not usable in DT.

Best regards,
Alexander
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