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mtd: rawnand: Provide helper for polling GPIO R/B pin 

Each controller driver having access to NAND R/B pin over GPIO would
have to reimplement the polling loop otherwise.

Suggested-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
This commit is contained in:
Janusz Krzysztofik 2018-10-15 21:41:28 +02:00 committed by Miquel Raynal
parent 41d6f0d07d
commit b0e137ad24
2 changed files with 35 additions and 0 deletions
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31
drivers/mtd/nand/raw/nand_base.c
View File

@ -45,6 +45,7 @@
#include <linux/io.h>
#include <linux/mtd/partitions.h>
#include <linux/of.h>
#include <linux/gpio/consumer.h>
#include "internals.h"
@ -531,6 +532,36 @@ int nand_soft_waitrdy(struct nand_chip *chip, unsigned long timeout_ms)
};
EXPORT_SYMBOL_GPL(nand_soft_waitrdy);
/**
* nand_gpio_waitrdy - Poll R/B GPIO pin until ready
* @chip: NAND chip structure
* @gpiod: GPIO descriptor of R/B pin
* @timeout_ms: Timeout in ms
*
* Poll the R/B GPIO pin until it becomes ready. If that does not happen
* whitin the specified timeout, -ETIMEDOUT is returned.
*
* This helper is intended to be used when the controller has access to the
* NAND R/B pin over GPIO.
*
* Return 0 if the R/B pin indicates chip is ready, a negative error otherwise.
*/
int nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod,
unsigned long timeout_ms)
{
/* Wait until R/B pin indicates chip is ready or timeout occurs */
timeout_ms = jiffies + msecs_to_jiffies(timeout_ms);
do {
if (gpiod_get_value_cansleep(gpiod))
return 0;
cond_resched();
} while (time_before(jiffies, timeout_ms));
return gpiod_get_value_cansleep(gpiod) ? 0 : -ETIMEDOUT;
};
EXPORT_SYMBOL_GPL(nand_gpio_waitrdy);
/**
* panic_nand_get_device - [GENERIC] Get chip for selected access
* @chip: the nand chip descriptor

4
include/linux/mtd/rawnand.h
View File

@ -1346,4 +1346,8 @@ void nand_release(struct nand_chip *chip);
*/
int nand_soft_waitrdy(struct nand_chip *chip, unsigned long timeout_ms);
struct gpio_desc;
int nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod,
unsigned long timeout_ms);
#endif /* __LINUX_MTD_RAWNAND_H */