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mmc: provide a standard MMC device-tree binding parser centrally 

MMC defines a number of standard DT bindings. Having each driver parse
them individually adds code redundancy and is error prone. Provide a
standard function to unify the parsing. After all drivers are converted
to using it instead of their own parsers, this function can be integrated
into mmc_alloc_host().

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Guennadi Liakhovetski 2013-02-16 16:21:16 +01:00 committed by Chris Ball
parent 6da15e96fb
commit 6c56e7a0ff
2 changed files with 111 additions and 0 deletions
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110
drivers/mmc/core/host.c
View File

@ -15,6 +15,8 @@
#include <linux/device.h>
#include <linux/err.h>
#include <linux/idr.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/pagemap.h>
#include <linux/export.h>
#include <linux/leds.h>
@ -23,6 +25,7 @@
#include <linux/mmc/host.h>
#include <linux/mmc/card.h>
#include <linux/mmc/slot-gpio.h>
#include "core.h"
#include "host.h"
@ -294,6 +297,113 @@ static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
#endif
/**
* mmc_of_parse() - parse host's device-tree node
* @host: host whose node should be parsed.
*
* To keep the rest of the MMC subsystem unaware of whether DT has been
* used to to instantiate and configure this host instance or not, we
* parse the properties and set respective generic mmc-host flags and
* parameters.
*/
void mmc_of_parse(struct mmc_host *host)
{
struct device_node *np;
u32 bus_width;
bool explicit_inv_wp, gpio_inv_wp = false;
enum of_gpio_flags flags;
int len, ret, gpio;
if (!host->parent || !host->parent->of_node)
return;
np = host->parent->of_node;
/* "bus-width" is translated to MMC_CAP_*_BIT_DATA flags */
if (of_property_read_u32(np, "bus-width", &bus_width) < 0) {
dev_dbg(host->parent,
"\"bus-width\" property is missing, assuming 1 bit.\n");
bus_width = 1;
}
switch (bus_width) {
case 8:
host->caps |= MMC_CAP_8_BIT_DATA;
/* Hosts capable of 8-bit transfers can also do 4 bits */
case 4:
host->caps |= MMC_CAP_4_BIT_DATA;
break;
case 1:
break;
default:
dev_err(host->parent,
"Invalid \"bus-width\" value %ud!\n", bus_width);
}
/* f_max is obtained from the optional "max-frequency" property */
of_property_read_u32(np, "max-frequency", &host->f_max);
/*
* Configure CD and WP pins. They are both by default active low to
* match the SDHCI spec. If GPIOs are provided for CD and / or WP, the
* mmc-gpio helpers are used to attach, configure and use them. If
* polarity inversion is specified in DT, one of MMC_CAP2_CD_ACTIVE_HIGH
* and MMC_CAP2_RO_ACTIVE_HIGH capability-2 flags is set. If the
* "broken-cd" property is provided, the MMC_CAP_NEEDS_POLL capability
* is set. If the "non-removable" property is found, the
* MMC_CAP_NONREMOVABLE capability is set and no card-detection
* configuration is performed.
*/
/* Parse Card Detection */
if (of_find_property(np, "non-removable", &len)) {
host->caps |= MMC_CAP_NONREMOVABLE;
} else {
bool explicit_inv_cd, gpio_inv_cd = false;
explicit_inv_cd = of_property_read_bool(np, "cd-inverted");
if (of_find_property(np, "broken-cd", &len))
host->caps |= MMC_CAP_NEEDS_POLL;
gpio = of_get_named_gpio_flags(np, "cd-gpios", 0, &flags);
if (gpio_is_valid(gpio)) {
if (!(flags & OF_GPIO_ACTIVE_LOW))
gpio_inv_cd = true;
ret = mmc_gpio_request_cd(host, gpio);
if (ret < 0)
dev_err(host->parent,
"Failed to request CD GPIO #%d: %d!\n",
gpio, ret);
else
dev_info(host->parent, "Got CD GPIO #%d.\n",
gpio);
}
if (explicit_inv_cd ^ gpio_inv_cd)
host->caps2 |= MMC_CAP2_CD_ACTIVE_HIGH;
}
/* Parse Write Protection */
explicit_inv_wp = of_property_read_bool(np, "wp-inverted");
gpio = of_get_named_gpio_flags(np, "wp-gpios", 0, &flags);
if (gpio_is_valid(gpio)) {
if (!(flags & OF_GPIO_ACTIVE_LOW))
gpio_inv_wp = true;
ret = mmc_gpio_request_ro(host, gpio);
if (ret < 0)
dev_err(host->parent,
"Failed to request WP GPIO: %d!\n", ret);
}
if (explicit_inv_wp ^ gpio_inv_wp)
host->caps2 |= MMC_CAP2_RO_ACTIVE_HIGH;
}
EXPORT_SYMBOL(mmc_of_parse);
/**
* mmc_alloc_host - initialise the per-host structure.
* @extra: sizeof private data structure

1
include/linux/mmc/host.h
View File

@ -368,6 +368,7 @@ extern struct mmc_host *mmc_alloc_host(int extra, struct device *);
extern int mmc_add_host(struct mmc_host *);
extern void mmc_remove_host(struct mmc_host *);
extern void mmc_free_host(struct mmc_host *);
void mmc_of_parse(struct mmc_host *host);
static inline void *mmc_priv(struct mmc_host *host)
{