Re: [U-Boot] [PATCH v1 1/3] drivers: gpio: Handle gracefully NULL pointers

Hi Jean-Jacques,

On Tue, 1 Oct 2019 at 05:51, Jean-Jacques Hiblot jjhiblot@ti.com wrote:

Prepare the way for a managed GPIO API by handling NULL pointers without crashing nor failing. VALIDATE_DESC() and validate_desc() come straight from Linux.

Signed-off-by: Jean-Jacques Hiblot jjhiblot@ti.com

drivers/gpio/gpio-uclass.c | 66 ++++++++++++++++++++++++++++++++------ include/asm-generic/gpio.h | 2 +- 2 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c index 01cfa2f788..63c10f438b 100644 --- a/drivers/gpio/gpio-uclass.c +++ b/drivers/gpio/gpio-uclass.c @@ -18,6 +18,33 @@

DECLARE_GLOBAL_DATA_PTR;

+/*

• • This descriptor validation needs to be inserted verbatim into each
• • function taking a descriptor, so we need to use a preprocessor
• • macro to avoid endless duplication. If the desc is NULL it is an
• • optional GPIO and calls should just bail out.
• */

+static int validate_desc(const struct gpio_desc *desc, const char *func) +{

•   if (!desc)
  

•           return 0;
  

•   if (IS_ERR(desc)) {
  

•           pr_warn("%s: invalid GPIO (errorpointer)\n", func);
  

•           return PTR_ERR(desc);
  

•   }
  

•   if (!desc->dev) {
  

•           pr_warn("%s: invalid GPIO (no device)\n", func);
  

•           return -EINVAL;
  

•   }
  

•   return 1;
  

+}

+#define VALIDATE_DESC(desc) do { \

•   int __valid = validate_desc(desc, __func__); \
  

•   if (__valid <= 0) \
  

•           return __valid; \
  

•   } while (0)
  

This adds to code size so should be behind a CONFIG I think.

/**

• gpio_to_device() - Convert global GPIO number to device, number

@@ -269,11 +296,14 @@ int gpio_hog_lookup_name(const char *name, struct gpio_desc **desc)

int dm_gpio_request(struct gpio_desc *desc, const char *label) {

•   struct udevice *dev = desc->dev;
  

•   struct udevice *dev;
    struct gpio_dev_priv *uc_priv;
    char *str;
    int ret;
  
  

•   VALIDATE_DESC(desc);
  

•   dev = desc->dev;
  

•   uc_priv = dev_get_uclass_priv(dev);
    if (uc_priv->name[desc->offset])
            return -EBUSY;
  

@@ -400,6 +430,8 @@ static int check_reserved(const struct gpio_desc *desc, const char *func) { struct gpio_dev_priv *uc_priv;

•   VALIDATE_DESC(desc);
  

•   if (!dm_gpio_is_valid(desc))
            return -ENOENT;
  
  

@@ -468,6 +500,8 @@ int dm_gpio_get_value(const struct gpio_desc *desc) int value; int ret;

•   VALIDATE_DESC(desc);
  

•   ret = check_reserved(desc, "get_value");
    if (ret)
            return ret;
  

@@ -481,6 +515,8 @@ int dm_gpio_set_value(const struct gpio_desc *desc, int value) { int ret;

•   VALIDATE_DESC(desc);
  

•   ret = check_reserved(desc, "set_value");
    if (ret)
            return ret;
  

@@ -493,9 +529,12 @@ int dm_gpio_set_value(const struct gpio_desc *desc, int value)

int dm_gpio_get_open_drain(struct gpio_desc *desc) {

•   struct dm_gpio_ops *ops = gpio_get_ops(desc->dev);
  

•   struct dm_gpio_ops *ops;
    int ret;
  
  

•   VALIDATE_DESC(desc);
  

•   ops = gpio_get_ops(desc->dev);
  

•   ret = check_reserved(desc, "get_open_drain");
    if (ret)
            return ret;
  

@@ -508,9 +547,12 @@ int dm_gpio_get_open_drain(struct gpio_desc *desc)

int dm_gpio_set_open_drain(struct gpio_desc *desc, int value) {

•   struct dm_gpio_ops *ops = gpio_get_ops(desc->dev);
  

•   struct dm_gpio_ops *ops;
    int ret;
  
  

•   VALIDATE_DESC(desc);
  

•   ops = gpio_get_ops(desc->dev);
  

•   ret = check_reserved(desc, "set_open_drain");
    if (ret)
            return ret;
  

@@ -525,10 +567,14 @@ int dm_gpio_set_open_drain(struct gpio_desc *desc, int value)

int dm_gpio_set_dir_flags(struct gpio_desc *desc, ulong flags) {

•   struct udevice *dev = desc->dev;
  

•   struct dm_gpio_ops *ops = gpio_get_ops(dev);
  

•   struct udevice *dev;
  

•   struct dm_gpio_ops *ops;
    int ret;
  
  

•   VALIDATE_DESC(desc);
  

•   dev = desc->dev;
  

•   ops = gpio_get_ops(dev);
  

•   ret = check_reserved(desc, "set_dir");
    if (ret)
            return ret;
  

@@ -570,7 +616,6 @@ int dm_gpio_set_dir(struct gpio_desc *desc) int gpio_get_value(unsigned gpio) { int ret;

unrelated change?

    struct gpio_desc desc;

    ret = gpio_to_device(gpio, &desc);

@@ -933,6 +978,8 @@ int gpio_get_list_count(struct udevice *dev, const char *list_name)

int dm_gpio_free(struct udevice *dev, struct gpio_desc *desc) {

•   VALIDATE_DESC(desc);
  

•   /* For now, we don't do any checking of dev */
    return _dm_gpio_free(desc->dev, desc->offset);
  

} @@ -981,12 +1028,11 @@ static int gpio_renumber(struct udevice *removed_dev)

int gpio_get_number(const struct gpio_desc *desc) {

•   struct udevice *dev = desc->dev;
    struct gpio_dev_priv *uc_priv;
  
  

•   if (!dev)
  

•           return -1;
  

•   uc_priv = dev->uclass_priv;
  

•   VALIDATE_DESC(desc);
  

I think this is pretty opaque. How about writing the code out in full, with a helper function to do the check. The helper function can return the error code perhaps.

ret = validate_desc(desc); if (ret) return log_msg_ret("gpio_free", ret);

Regards, Simon

•   uc_priv = dev_get_uclass_priv(desc->dev);
  
    return uc_priv->gpio_base + desc->offset;
  

} diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index d6cf18744f..ba669b65a9 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -139,7 +139,7 @@ struct gpio_desc { */ static inline bool dm_gpio_is_valid(const struct gpio_desc *desc) {

•   return desc->dev != NULL;
  

•   return desc && desc->dev;
  

}

/**

2.17.1