Re: [PATCH V3 1/2] mtd: allow getting MTD device associated with a specific DT node

Miquel Raynal
2022-06-13T14:33:58Z

Hi Rafał,

zajec5@gmail.com wrote on Mon, 13 Jun 2022 16:15:34 +0200:

> On 13.06.2022 16:04, Miquel Raynal wrote:
> >> @@ -1154,6 +1154,34 @@ int __get_mtd_device(struct mtd_info *mtd)
> >> }
> >> EXPORT_SYMBOL_GPL(__get_mtd_device);
> >> >> +/**
> >> + * of_get_mtd_device_by_node - obtain an MTD device associated with a given node
> >> + *
> >> + * @np: device tree node
> >> + */
> >> +struct mtd_info *of_get_mtd_device_by_node(struct device_node *np)
> >
> > Shall we try to use a more of-agnostic syntax or is it too complex here?
>
> I need some extra hint, please. This is how many similar functions look
> like:

I know most implementation today use of_ functions directly but it
seems like there is a global move towards fwnodes now, and I was
wondering if using those instead (which might also apply to other types
of "nodes" than DT ones) could be possible.

But looking into existing implementations, I came across the pwm implem
which features:
- of_pwm_get()
- acpi_pwm_get()

And finally a fwnode_pwm_get() which does:

if (is_of_node())
of_pwm_get():
else if (is_acpi_node())
acpi_pwm_get();

So actually my suggestion is meaningless. I'm fine with the current
approach.

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

>
> $ grep -E -r "(get|find).*_by_node" ./include/*
> ./include/drm/drm_mipi_dsi.h:struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
> ./include/drm/drm_mipi_dsi.h:struct mipi_dsi_device *of_find_mipi_dsi_device_by_node(struct device_node *np);
> ./include/linux/usb/phy.h:extern struct usb_phy *devm_usb_get_phy_by_node(struct device *dev,
> ./include/linux/usb/phy.h:static inline struct usb_phy *devm_usb_get_phy_by_node(struct device *dev,
> ./include/linux/extcon.h:struct extcon_dev *extcon_find_edev_by_node(struct device_node *node);
> ./include/linux/extcon.h:static inline struct extcon_dev *extcon_find_edev_by_node(struct device_node *node)
> ./include/linux/of_net.h:extern struct net_device *of_find_net_device_by_node(struct device_node *np);
> ./include/linux/of_net.h:static inline struct net_device *of_find_net_device_by_node(struct device_node *np)
> ./include/linux/devfreq.h:struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node);
> ./include/linux/devfreq.h:static inline struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node)
> ./include/linux/of_platform.h:extern struct platform_device *of_find_device_by_node(struct device_node *np);
> ./include/linux/of_platform.h:static inline struct platform_device *of_find_device_by_node(struct device_node *np)
> ./include/linux/backlight.h:struct backlight_device *of_find_backlight_by_node(struct device_node *node);
> ./include/linux/backlight.h:of_find_backlight_by_node(struct device_node *node)
> ./include/linux/i2c.h:struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
> ./include/linux/i2c.h:struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);
> ./include/linux/i2c.h:struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node);
> ./include/linux/i2c.h:static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
> ./include/linux/i2c.h:static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
> ./include/linux/i2c.h:static inline struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node)
>
>
> >> +{
> >> + struct mtd_info *mtd = NULL;
> >> + struct mtd_info *tmp;
> >> + int err;
> >> +
> >> + mutex_lock(&mtd_table_mutex);
> >> +
> >> + err = -ENODEV;
> >> + mtd_for_each_device(tmp) {
> >> + if (mtd_get_of_node(tmp) == np) {
> >> + mtd = tmp;
> >> + err = __get_mtd_device(mtd);
> >> + break;
> >> + }
> >> + }
> >> +
> >> + mutex_unlock(&mtd_table_mutex);
> >> +
> >> + return err ? ERR_PTR(err) : mtd;
> >> +}
> >> +EXPORT_SYMBOL_GPL(of_get_mtd_device_by_node);
> >> +
> >> /**
> >> * get_mtd_device_nm - obtain a validated handle for an MTD device by
> >> * device name
>

Thanks,
Miquèl