linux-kernel - Re: [PATCH 2/2] mmc: dw_mmc: Handle wp-gpios from device tree

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Message-id: <50AD862D.40302@samsung.com>
Date:	Thu, 22 Nov 2012 10:55:57 +0900
From:	Jaehoon Chung <jh80.chung@...sung.com>
To:	Doug Anderson <dianders@...omium.org>
Cc:	linux-samsung-soc@...r.kernel.org,
	Thomas Abraham <thomas.abraham@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Olof Johansson <olof@...om.net>, Arnd Bergmann <arnd@...db.de>,
	Will Newton <will.newton@...tec.com>,
	Chris Ball <cjb@...top.org>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mmc: dw_mmc: Handle wp-gpios from device tree

On 11/22/2012 07:03 AM, Doug Anderson wrote:
> On some SoCs (like exynos5250) you need to use an external GPIO for
> write protect.  Add support for wp-gpios to the core dw_mmc driver
> since it could be useful across multiple SoCs.
> 
> With this change I am able to make use of the write protect for the
> external SD slot on exynos5250-snow.
> 
> Signed-off-by: Doug Anderson <dianders@...omium.org>
> ---
>  drivers/mmc/host/dw_mmc.c |   35 +++++++++++++++++++++++++++++++++++
>  1 files changed, 35 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 5b41348..9c79870 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -34,6 +34,7 @@
>  #include <linux/regulator/consumer.h>
>  #include <linux/workqueue.h>
>  #include <linux/of.h>
> +#include <linux/of_gpio.h>
>  
>  #include "dw_mmc.h"
>  
> @@ -74,6 +75,7 @@ struct idmac_desc {
>   * struct dw_mci_slot - MMC slot state
>   * @mmc: The mmc_host representing this slot.
>   * @host: The MMC controller this slot is using.
> + * @wp_gpio: If gpio_is_valid() we'll use this to read write protect.
>   * @ctype: Card type for this slot.
>   * @mrq: mmc_request currently being processed or waiting to be
>   *	processed, or NULL when the slot is idle.
> @@ -88,6 +90,8 @@ struct dw_mci_slot {
>  	struct mmc_host		*mmc;
>  	struct dw_mci		*host;
>  
> +	int			wp_gpio;
> +
>  	u32			ctype;
>  
>  	struct mmc_request	*mrq;
> @@ -832,6 +836,8 @@ static int dw_mci_get_ro(struct mmc_host *mmc)
>  		read_only = 0;
>  	else if (brd->get_ro)
>  		read_only = brd->get_ro(slot->id);
> +	else if (gpio_is_valid(slot->wp_gpio))
> +		read_only = gpio_get_value(slot->wp_gpio);
>  	else
>  		read_only =
>  			mci_readl(slot->host, WRTPRT) & (1 << slot->id) ? 1 : 0;
> @@ -1802,6 +1808,29 @@ static u32 dw_mci_of_get_bus_wd(struct device *dev, u8 slot)
>  			       " as 1\n");
>  	return bus_wd;
>  }
> +
> +/* find the write protect gpio for a given slot; or -1 if none specified */
> +static u32 dw_mci_of_get_wp_gpio(struct device *dev, u8 slot)
> +{
> +	struct device_node *np = dw_mci_of_find_slot_node(dev, slot);
> +	int gpio;
> +
> +	if (!np)
> +		return -1;
I think good that use the error number instead of -1. Also the below code.

> +
> +	gpio = of_get_named_gpio(np, "wp-gpios", 0);
> +
> +	/* Having a missing entry is valid; return silently */
> +	if (!gpio_is_valid(gpio))
> +		return -1;
> +
> +	if (devm_gpio_request(dev, gpio, "dw-mci-wp")) {
> +		dev_warn(dev, "gpio [%d] request failed\n", gpio);
> +		return -1;
> +	}
> +
> +	return gpio;
gpio is int type, but return type is u32?

Best Regards,
Jaehoon Chung
> +}
>  #else /* CONFIG_OF */
>  static u32 dw_mci_of_get_bus_wd(struct device *dev, u8 slot)
>  {
> @@ -1811,6 +1840,10 @@ static struct device_node *dw_mci_of_find_slot_node(struct device *dev, u8 slot)
>  {
>  	return NULL;
>  }
> +static u32 dw_mci_of_get_wp_gpio(struct device *dev, u8 slot)
> +{
> +	return -1;
> +}
>  #endif /* CONFIG_OF */
>  
>  static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
> @@ -1923,6 +1956,8 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
>  	else
>  		clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);
>  
> +	slot->wp_gpio = dw_mci_of_get_wp_gpio(host->dev, slot->id);
> +
>  	mmc_add_host(mmc);
>  
>  #if defined(CONFIG_DEBUG_FS)
> 

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