2020-04-27 18:42:38

by Michael Auchter

Subject: [PATCH] nvmem: ensure sysfs writes handle write-protect pin

Commit 2a127da461a9d8d97782d6e82b227041393eb4d2 added support for
handling write-protect pins to the nvmem core, and commit
1c89074bf85068d1b86f2e0f0c2110fdd9b83c9f retrofitted the at24 driver to
use this support.

These changes broke write() on the nvmem sysfs attribute for eeproms
which utilize a write-protect pin, as the write callback invokes the
nvmem device's reg_write callback directly which no longer handles
changing the state of the write-protect pin.

Change the read and write callbacks for the sysfs attribute to invoke
nvmme_reg_read/nvmem_reg_write helpers which handle this, rather than
calling reg_read/reg_write directly.

Signed-off-by: Michael Auchter <[email protected]>
---
drivers/nvmem/core.c | 52 ++++++++++++++++++++++----------------------
1 file changed, 26 insertions(+), 26 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 05c6ae4b0b97..a8300202a7fb 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -66,6 +66,30 @@ static LIST_HEAD(nvmem_lookup_list);

static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);

+static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
+ void *val, size_t bytes)
+{
+ if (nvmem->reg_read)
+ return nvmem->reg_read(nvmem->priv, offset, val, bytes);
+
+ return -EINVAL;
+}
+
+static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
+ void *val, size_t bytes)
+{
+ int ret;
+
+ if (nvmem->reg_write) {
+ gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
+ ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
+ gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
+ return ret;
+ }
+
+ return -EINVAL;
+}
+
#ifdef CONFIG_NVMEM_SYSFS
static const char * const nvmem_type_str[] = {
[NVMEM_TYPE_UNKNOWN] = "Unknown",
@@ -122,7 +146,7 @@ static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
if (!nvmem->reg_read)
return -EPERM;

- rc = nvmem->reg_read(nvmem->priv, pos, buf, count);
+ rc = nvmem_reg_read(nvmem, pos, buf, count);

if (rc)
return rc;
@@ -159,7 +183,7 @@ static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
if (!nvmem->reg_write)
return -EPERM;

- rc = nvmem->reg_write(nvmem->priv, pos, buf, count);
+ rc = nvmem_reg_write(nvmem, pos, buf, count);

if (rc)
return rc;
@@ -311,30 +335,6 @@ static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,

#endif /* CONFIG_NVMEM_SYSFS */

-static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
- void *val, size_t bytes)
-{
- if (nvmem->reg_read)
- return nvmem->reg_read(nvmem->priv, offset, val, bytes);
-
- return -EINVAL;
-}
-
-static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
- void *val, size_t bytes)
-{
- int ret;
-
- if (nvmem->reg_write) {
- gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
- ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
- gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
- return ret;
- }
-
- return -EINVAL;
-}
-
static void nvmem_release(struct device *dev)
{
struct nvmem_device *nvmem = to_nvmem_device(dev);
--
2.25.1

2020-04-28 11:57:24

by Srinivas Kandagatla

Subject: Re: [PATCH] nvmem: ensure sysfs writes handle write-protect pin

On 27/04/2020 19:39, Michael Auchter wrote:
> Commit 2a127da461a9d8d97782d6e82b227041393eb4d2 added support for
> handling write-protect pins to the nvmem core, and commit
> 1c89074bf85068d1b86f2e0f0c2110fdd9b83c9f retrofitted the at24 driver to
> use this support.
>
> These changes broke write() on the nvmem sysfs attribute for eeproms
> which utilize a write-protect pin, as the write callback invokes the
> nvmem device's reg_write callback directly which no longer handles
> changing the state of the write-protect pin.
>
> Change the read and write callbacks for the sysfs attribute to invoke
> nvmme_reg_read/nvmem_reg_write helpers which handle this, rather than
> calling reg_read/reg_write directly.
>
> Signed-off-by: Michael Auchter <[email protected]>
> ---
> drivers/nvmem/core.c | 52 ++++++++++++++++++++++----------------------
> 1 file changed, 26 insertions(+), 26 deletions(-)
>

Applied fixes tag:
Fixes: 2a127da461a9 ("nvmem: add support for the write-protect pin")


--srini