[PATCH 02/15] mtd: nand: base: implement nand_gpio_waitrdy

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

To simplify porting kernel NAND drivers a tiny bit, provide the Linux
nand_gpio_waitrdy. This is readily implementable with barebox' own
gpio_poll_timeout_us.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/mtd/nand/nand_base.c | 22 ++++++++++++++++++++++
 include/linux/mtd/rawnand.h  |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 4c90ad975771..c3cd22935bb2 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -36,6 +36,7 @@
 #include <asm/byteorder.h>
 #include <io.h>
 #include <malloc.h>
+#include <gpio.h>
 #include <module.h>
 #include <of_mtd.h>
 
@@ -785,6 +786,27 @@ 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, int gpio,
+		      unsigned long timeout_ms)
+{
+	return gpio_poll_timeout_us(gpio, true, timeout_ms * USEC_PER_MSEC);
+};
+EXPORT_SYMBOL_GPL(nand_gpio_waitrdy);
+
 static bool nand_supports_get_features(struct nand_chip *chip, int addr)
 {
 	return (chip->parameters.supports_set_get_features &&
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index 1147f235a680..a05c67e1404b 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -1414,6 +1414,8 @@ void nand_cleanup(struct nand_chip *chip);
  * instruction and have no physical pin to check it.
  */
 int nand_soft_waitrdy(struct nand_chip *chip, unsigned long timeout_ms);
+int nand_gpio_waitrdy(struct nand_chip *chip, int gpio,
+		      unsigned long timeout_ms);
 
 /* Select/deselect a NAND target. */
 void nand_select_target(struct nand_chip *chip, unsigned int cs);
-- 
2.30.2