| Message ID | 20200107092922.18408-3-ktouil@baylibre.com |
|---|---|
| State | Accepted |
| Delegated to: | Bartosz Golaszewski |
| Headers | show |
| Series | at24: move write-protect pin handling to nvmem core | expand |
Hi Khouloud, On Tue, Jan 7, 2020 at 10:30 AM Khouloud Touil <ktouil@baylibre.com> wrote: > The write-protect pin handling looks like a standard property that > could benefit other users if available in the core nvmem framework. > > Instead of modifying all the memory drivers to check this pin, make > the NVMEM subsystem check if the write-protect GPIO being passed > through the nvmem_config or defined in the device tree and pull it > low whenever writing to the memory. > > There was a suggestion for introducing the gpiodesc from pdata, but > as pdata is already removed it could be replaced by adding it to > nvmem_config. > > Reference: https://lists.96boards.org/pipermail/dev/2018-August/001056.html > > Signed-off-by: Khouloud Touil <ktouil@baylibre.com> > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> Thanks for your patch! > --- a/drivers/nvmem/core.c > +++ b/drivers/nvmem/core.c > @@ -15,6 +15,7 @@ > #include <linux/module.h> > #include <linux/nvmem-consumer.h> > #include <linux/nvmem-provider.h> > +#include <linux/gpio/consumer.h> > #include <linux/of.h> > #include <linux/slab.h> > #include "nvmem.h" > @@ -54,8 +55,14 @@ static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset, > static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset, > void *val, size_t bytes) > { > - if (nvmem->reg_write) > - return nvmem->reg_write(nvmem->priv, offset, val, 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; > } > @@ -338,6 +345,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > kfree(nvmem); > return ERR_PTR(rval); > } > + if (config->wp_gpio) > + nvmem->wp_gpio = config->wp_gpio; > + else > + nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp", > + GPIOD_OUT_HIGH); Shouldn't this GPIO be released in nvmem_release(), by calling gpiod_put()? Once that's implemented, I assume it will be auto-released on registration failure by the call to put_device()? > + if (IS_ERR(nvmem->wp_gpio)) > + return PTR_ERR(nvmem->wp_gpio); > + > > kref_init(&nvmem->refcnt); > INIT_LIST_HEAD(&nvmem->cells); Gr{oetje,eeting}s, Geert
Le jeu. 30 janv. 2020 à 09:06, Geert Uytterhoeven <geert@linux-m68k.org> a écrit : > > Hi Khouloud, > > On Tue, Jan 7, 2020 at 10:30 AM Khouloud Touil <ktouil@baylibre.com> wrote: > > The write-protect pin handling looks like a standard property that > > could benefit other users if available in the core nvmem framework. > > > > Instead of modifying all the memory drivers to check this pin, make > > the NVMEM subsystem check if the write-protect GPIO being passed > > through the nvmem_config or defined in the device tree and pull it > > low whenever writing to the memory. > > > > There was a suggestion for introducing the gpiodesc from pdata, but > > as pdata is already removed it could be replaced by adding it to > > nvmem_config. > > > > Reference: https://lists.96boards.org/pipermail/dev/2018-August/001056.html > > > > Signed-off-by: Khouloud Touil <ktouil@baylibre.com> > > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > > Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > > Thanks for your patch! > > > --- a/drivers/nvmem/core.c > > +++ b/drivers/nvmem/core.c > > @@ -15,6 +15,7 @@ > > #include <linux/module.h> > > #include <linux/nvmem-consumer.h> > > #include <linux/nvmem-provider.h> > > +#include <linux/gpio/consumer.h> > > #include <linux/of.h> > > #include <linux/slab.h> > > #include "nvmem.h" > > @@ -54,8 +55,14 @@ static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset, > > static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset, > > void *val, size_t bytes) > > { > > - if (nvmem->reg_write) > > - return nvmem->reg_write(nvmem->priv, offset, val, 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; > > } > > @@ -338,6 +345,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > > kfree(nvmem); > > return ERR_PTR(rval); > > } > > + if (config->wp_gpio) > > + nvmem->wp_gpio = config->wp_gpio; > > + else > > + nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp", > > + GPIOD_OUT_HIGH); > > Shouldn't this GPIO be released in nvmem_release(), by calling gpiod_put()? > > Once that's implemented, I assume it will be auto-released on registration > failure by the call to put_device()? Hello Geert, Thanks for your review. Yes you are right, I will add that Khouloud, > > > + if (IS_ERR(nvmem->wp_gpio)) > > + return PTR_ERR(nvmem->wp_gpio); > > + > > > > kref_init(&nvmem->refcnt); > > INIT_LIST_HEAD(&nvmem->cells); > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds
czw., 30 sty 2020 o 09:06 Geert Uytterhoeven <geert@linux-m68k.org> napisał(a): > > Hi Khouloud, > > On Tue, Jan 7, 2020 at 10:30 AM Khouloud Touil <ktouil@baylibre.com> wrote: > > The write-protect pin handling looks like a standard property that > > could benefit other users if available in the core nvmem framework. > > > > Instead of modifying all the memory drivers to check this pin, make > > the NVMEM subsystem check if the write-protect GPIO being passed > > through the nvmem_config or defined in the device tree and pull it > > low whenever writing to the memory. > > > > There was a suggestion for introducing the gpiodesc from pdata, but > > as pdata is already removed it could be replaced by adding it to > > nvmem_config. > > > > Reference: https://lists.96boards.org/pipermail/dev/2018-August/001056.html > > > > Signed-off-by: Khouloud Touil <ktouil@baylibre.com> > > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > > Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > > Thanks for your patch! > > > --- a/drivers/nvmem/core.c > > +++ b/drivers/nvmem/core.c > > @@ -15,6 +15,7 @@ > > #include <linux/module.h> > > #include <linux/nvmem-consumer.h> > > #include <linux/nvmem-provider.h> > > +#include <linux/gpio/consumer.h> > > #include <linux/of.h> > > #include <linux/slab.h> > > #include "nvmem.h" > > @@ -54,8 +55,14 @@ static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset, > > static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset, > > void *val, size_t bytes) > > { > > - if (nvmem->reg_write) > > - return nvmem->reg_write(nvmem->priv, offset, val, 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; > > } > > @@ -338,6 +345,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > > kfree(nvmem); > > return ERR_PTR(rval); > > } > > + if (config->wp_gpio) > > + nvmem->wp_gpio = config->wp_gpio; > > + else > > + nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp", > > + GPIOD_OUT_HIGH); > > Shouldn't this GPIO be released in nvmem_release(), by calling gpiod_put()? > Hi Geert, Khouloud already sent out a patch but I think it still doesn't fix all the problems. While we should call gpiod_put() for the descs we request - we must not do it for the desc we get over the config structure. Unless... we make descs reference counted with kref and add gpiod_ref() helper. That way we could increase the reference counter in the upper branch of the if and not do it in the lower. Calling gpiod_put() would internally call kref_put(). Does it make sense? I think that a function that's called gpiod_put() but doesn't really use reference counting is misleading anyway. > Once that's implemented, I assume it will be auto-released on registration > failure by the call to put_device()? No, I think this is another leak - why would put_device() lead to freeing any resources? Am I missing something? Bart
Hi Bartosz, On Mon, Feb 17, 2020 at 3:34 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote: > czw., 30 sty 2020 o 09:06 Geert Uytterhoeven <geert@linux-m68k.org> napisał(a): > > On Tue, Jan 7, 2020 at 10:30 AM Khouloud Touil <ktouil@baylibre.com> wrote: > > > The write-protect pin handling looks like a standard property that > > > could benefit other users if available in the core nvmem framework. > > > > > > Instead of modifying all the memory drivers to check this pin, make > > > the NVMEM subsystem check if the write-protect GPIO being passed > > > through the nvmem_config or defined in the device tree and pull it > > > low whenever writing to the memory. > > > > > > There was a suggestion for introducing the gpiodesc from pdata, but > > > as pdata is already removed it could be replaced by adding it to > > > nvmem_config. > > > > > > Reference: https://lists.96boards.org/pipermail/dev/2018-August/001056.html > > > > > > Signed-off-by: Khouloud Touil <ktouil@baylibre.com> > > > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > > > Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > > > > Thanks for your patch! > > > > > --- a/drivers/nvmem/core.c > > > +++ b/drivers/nvmem/core.c > > > @@ -15,6 +15,7 @@ > > > #include <linux/module.h> > > > #include <linux/nvmem-consumer.h> > > > #include <linux/nvmem-provider.h> > > > +#include <linux/gpio/consumer.h> > > > #include <linux/of.h> > > > #include <linux/slab.h> > > > #include "nvmem.h" > > > @@ -54,8 +55,14 @@ static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset, > > > static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset, > > > void *val, size_t bytes) > > > { > > > - if (nvmem->reg_write) > > > - return nvmem->reg_write(nvmem->priv, offset, val, 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; > > > } > > > @@ -338,6 +345,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > > > kfree(nvmem); > > > return ERR_PTR(rval); > > > } > > > + if (config->wp_gpio) > > > + nvmem->wp_gpio = config->wp_gpio; > > > + else > > > + nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp", > > > + GPIOD_OUT_HIGH); > > > > Shouldn't this GPIO be released in nvmem_release(), by calling gpiod_put()? > > > > Hi Geert, > > Khouloud already sent out a patch but I think it still doesn't fix all > the problems. > > While we should call gpiod_put() for the descs we request - we must > not do it for the desc we get over the config structure. Unless... we That's true. > make descs reference counted with kref and add gpiod_ref() helper. > That way we could increase the reference counter in the upper branch > of the if and not do it in the lower. Calling gpiod_put() would > internally call kref_put(). Does it make sense? I think that a > function that's called gpiod_put() but doesn't really use reference > counting is misleading anyway. Yep. > > Once that's implemented, I assume it will be auto-released on registration > > failure by the call to put_device()? > > No, I think this is another leak - why would put_device() lead to > freeing any resources? Am I missing something? Sorry, I don't remember why I wrote that part... Anyway, requested GPIOs should be released on failure, and on unregistration. Gr{oetje,eeting}s, Geert
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 9f1ee9c766ec..3e1c94c4eee8 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -15,6 +15,7 @@ #include <linux/module.h> #include <linux/nvmem-consumer.h> #include <linux/nvmem-provider.h> +#include <linux/gpio/consumer.h> #include <linux/of.h> #include <linux/slab.h> #include "nvmem.h" @@ -54,8 +55,14 @@ static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset, static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset, void *val, size_t bytes) { - if (nvmem->reg_write) - return nvmem->reg_write(nvmem->priv, offset, val, 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; } @@ -338,6 +345,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) kfree(nvmem); return ERR_PTR(rval); } + if (config->wp_gpio) + nvmem->wp_gpio = config->wp_gpio; + else + nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp", + GPIOD_OUT_HIGH); + if (IS_ERR(nvmem->wp_gpio)) + return PTR_ERR(nvmem->wp_gpio); + kref_init(&nvmem->refcnt); INIT_LIST_HEAD(&nvmem->cells); diff --git a/drivers/nvmem/nvmem.h b/drivers/nvmem/nvmem.h index eb8ed7121fa3..be0d66d75c8a 100644 --- a/drivers/nvmem/nvmem.h +++ b/drivers/nvmem/nvmem.h @@ -9,6 +9,7 @@ #include <linux/list.h> #include <linux/nvmem-consumer.h> #include <linux/nvmem-provider.h> +#include <linux/gpio/consumer.h> struct nvmem_device { struct module *owner; @@ -26,6 +27,7 @@ struct nvmem_device { struct list_head cells; nvmem_reg_read_t reg_read; nvmem_reg_write_t reg_write; + struct gpio_desc *wp_gpio; void *priv; }; diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h index fe051323be0a..6d6f8e5d24c9 100644 --- a/include/linux/nvmem-provider.h +++ b/include/linux/nvmem-provider.h @@ -11,6 +11,7 @@ #include <linux/err.h> #include <linux/errno.h> +#include <linux/gpio/consumer.h> struct nvmem_device; struct nvmem_cell_info; @@ -45,6 +46,7 @@ enum nvmem_type { * @word_size: Minimum read/write access granularity. * @stride: Minimum read/write access stride. * @priv: User context passed to read/write callbacks. + * @wp-gpio: Write protect pin * * Note: A default "nvmem<id>" name will be assigned to the device if * no name is specified in its configuration. In such case "<id>" is @@ -58,6 +60,7 @@ struct nvmem_config { const char *name; int id; struct module *owner; + struct gpio_desc *wp_gpio; const struct nvmem_cell_info *cells; int ncells; enum nvmem_type type;