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Commit b0e137ad authored by Janusz Krzysztofik's avatar Janusz Krzysztofik Committed by Miquel Raynal
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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: default avatarBoris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: default avatarJanusz Krzysztofik <jmkrzyszt@gmail.com>
Reviewed-by: default avatarBoris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
parent 41d6f0d0

drivers/mtd/nand/raw/nand_base.c

+31 −0
Original line number Diff line number Diff line
@@ -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

include/linux/mtd/rawnand.h

+4 −0
Original line number Diff line number Diff line
@@ -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 */