[PATCH v2 0/3] nvmem: meson-efuse: add write support

[PATCH v2 0/3] nvmem: meson-efuse: add write support

[Jerome Brunet]

This changeset adds write support to meson efuse driver.
The first patch just changes the way the nvmem data are allocated w/o
any functional changes. The second patches actually adds write support.

The memory being an OTP, it is safer if it remains read-only by default,
which is why I also submitted this DT patch [0]. It has now been merged by
Kevin.

If a user knows what he is doing, it should be easy to remove the
read-only property from the board DT. This can be done in u-boot, before
starting linux:

 > fdt rm /efuse read-only

Tested on the gxl libretech-cc

Changes since v1 [1]:
 - Remove un-necessary code in callbacks
 - Rebase on v4.17-rc1

[0]: https://lkml.kernel.org/r/20180316145021.8517-1-jbrunet@baylibre.com
[1]: https://lkml.kernel.org/r/20180316150113.9779-1-jbrunet@baylibre.com

Jerome Brunet (3):
  nvmem: meson-efuse: remove econfig global
  nvmem: meson-efuse: simplify read callback
  nvmem: meson-efuse: add write support

 drivers/nvmem/meson-efuse.c | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

-- 
2.14.3

[PATCH v2 1/3] nvmem: meson-efuse: remove econfig global

[Jerome Brunet]

Having a global structure holding a reference to the device
structure is not very nice. Allocate the econfig instead and fill
the nvmem information as before

Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/nvmem/meson-efuse.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/nvmem/meson-efuse.c b/drivers/nvmem/meson-efuse.c
index 71823d1403c5..2df9b0094f45 100644
--- a/drivers/nvmem/meson-efuse.c
+++ b/drivers/nvmem/meson-efuse.c
@@ -35,13 +35,6 @@ static int meson_efuse_read(void *context, unsigned int offset,
 	return 0;
 }
 
-static struct nvmem_config econfig = {
-	.name = "meson-efuse",
-	.stride = 1,
-	.word_size = 1,
-	.read_only = true,
-};
-
 static const struct of_device_id meson_efuse_match[] = {
 	{ .compatible = "amlogic,meson-gxbb-efuse", },
 	{ /* sentinel */ },
@@ -50,17 +43,27 @@ MODULE_DEVICE_TABLE(of, meson_efuse_match);
 
 static int meson_efuse_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	struct nvmem_device *nvmem;
+	struct nvmem_config *econfig;
 	unsigned int size;
 
 	if (meson_sm_call(SM_EFUSE_USER_MAX, &size, 0, 0, 0, 0, 0) < 0)
 		return -EINVAL;
 
-	econfig.dev = &pdev->dev;
-	econfig.reg_read = meson_efuse_read;
-	econfig.size = size;
+	econfig = devm_kzalloc(dev, sizeof(*econfig), GFP_KERNEL);
+	if (!econfig)
+		return -ENOMEM;
+
+	econfig->dev = dev;
+	econfig->name = dev_name(dev);
+	econfig->stride = 1;
+	econfig->word_size = 1;
+	econfig->read_only = true;
+	econfig->reg_read = meson_efuse_read;
+	econfig->size = size;
 
-	nvmem = devm_nvmem_register(&pdev->dev, &econfig);
+	nvmem = devm_nvmem_register(&pdev->dev, econfig);
 
 	return PTR_ERR_OR_ZERO(nvmem);
 }
-- 
2.14.3

[PATCH v2 2/3] nvmem: meson-efuse: simplify read callback

[Jerome Brunet]

Most of the code and variables in the read callback is not necessary.
Keep only what is required.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/nvmem/meson-efuse.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/nvmem/meson-efuse.c b/drivers/nvmem/meson-efuse.c
index 2df9b0094f45..4623249dfd87 100644
--- a/drivers/nvmem/meson-efuse.c
+++ b/drivers/nvmem/meson-efuse.c
@@ -24,15 +24,8 @@
 static int meson_efuse_read(void *context, unsigned int offset,
 			    void *val, size_t bytes)
 {
-	u8 *buf = val;
-	int ret;
-
-	ret = meson_sm_call_read(buf, bytes, SM_EFUSE_READ, offset,
-				 bytes, 0, 0, 0);
-	if (ret < 0)
-		return ret;
-
-	return 0;
+	return meson_sm_call_read((u8 *)val, bytes, SM_EFUSE_READ, offset,
+				  bytes, 0, 0, 0);
 }
 
 static const struct of_device_id meson_efuse_match[] = {
-- 
2.14.3

[PATCH v2 3/3] nvmem: meson-efuse: add write support

[Jerome Brunet]

Add write support to the meson-gx efuse driver.
Beware, this efuse is one time programmable !

Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/nvmem/meson-efuse.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/meson-efuse.c b/drivers/nvmem/meson-efuse.c
index 4623249dfd87..d769840d1e18 100644
--- a/drivers/nvmem/meson-efuse.c
+++ b/drivers/nvmem/meson-efuse.c
@@ -28,6 +28,13 @@ static int meson_efuse_read(void *context, unsigned int offset,
 				  bytes, 0, 0, 0);
 }
 
+static int meson_efuse_write(void *context, unsigned int offset,
+			     void *val, size_t bytes)
+{
+	return meson_sm_call_write((u8 *)val, bytes, SM_EFUSE_WRITE, offset,
+				   bytes, 0, 0, 0);
+}
+
 static const struct of_device_id meson_efuse_match[] = {
 	{ .compatible = "amlogic,meson-gxbb-efuse", },
 	{ /* sentinel */ },
@@ -52,8 +59,8 @@ static int meson_efuse_probe(struct platform_device *pdev)
 	econfig->name = dev_name(dev);
 	econfig->stride = 1;
 	econfig->word_size = 1;
-	econfig->read_only = true;
 	econfig->reg_read = meson_efuse_read;
+	econfig->reg_write = meson_efuse_write;
 	econfig->size = size;
 
 	nvmem = devm_nvmem_register(&pdev->dev, econfig);
-- 
2.14.3