[PATCH 07/12] spi: add support to setup spi-cs-{setup,hold,inactive}-delay-ns

[Marco Felsch]

Add support to parse and setup the common OF CS delay properties. The
parsing is quite confusing since the kernel driver API decided to use a
u16 for the value. I kept it this way to be closer to the Linux code.

This prepares the core for the upcoming core based message handling.

Signed-off-by: Marco Felsch <m.felsch at pengutronix.de>
---
 drivers/spi/spi.c | 25 +++++++++++++++++++++++++
 include/spi/spi.h | 22 ++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index c239de9d8549..e8a0b1b84be5 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -70,6 +70,9 @@ struct spi_device *spi_new_device(struct spi_controller *ctrl,
 		proxy->cs_gpiod = ctrl->cs_gpiods[chip->chip_select];
 	proxy->max_speed_hz = chip->max_speed_hz;
 	proxy->mode = chip->mode;
+	proxy->cs_setup = chip->cs_setup;
+	proxy->cs_hold = chip->cs_hold;
+	proxy->cs_inactive = chip->cs_inactive;
 	proxy->bits_per_word = chip->bits_per_word ? chip->bits_per_word : 8;
 	proxy->dev.platform_data = chip->platform_data;
 	proxy->dev.bus = &spi_bus;
@@ -111,6 +114,22 @@ struct spi_device *spi_new_device(struct spi_controller *ctrl,
 }
 EXPORT_SYMBOL(spi_new_device);
 
+static void of_spi_parse_dt_cs_delay(struct device_node *nc,
+				     struct spi_delay *delay, const char *prop)
+{
+	u32 value;
+
+	if (!of_property_read_u32(nc, prop, &value)) {
+		if (value > U16_MAX) {
+			delay->value = DIV_ROUND_UP(value, 1000);
+			delay->unit = SPI_DELAY_UNIT_USECS;
+		} else {
+			delay->value = value;
+			delay->unit = SPI_DELAY_UNIT_NSECS;
+		}
+	}
+}
+
 static void spi_of_register_slaves(struct spi_controller *ctrl)
 {
 	struct device_node *n;
@@ -145,6 +164,12 @@ static void spi_of_register_slaves(struct spi_controller *ctrl)
 			chip.mode |= SPI_3WIRE;
 		of_property_read_u32(n, "spi-max-frequency",
 				&chip.max_speed_hz);
+
+		/* Device CS delays */
+		of_spi_parse_dt_cs_delay(n, &chip.cs_setup, "spi-cs-setup-delay-ns");
+		of_spi_parse_dt_cs_delay(n, &chip.cs_hold, "spi-cs-hold-delay-ns");
+		of_spi_parse_dt_cs_delay(n, &chip.cs_inactive, "spi-cs-inactive-delay-ns");
+
 		reg = of_find_property(n, "reg", NULL);
 		if (!reg)
 			continue;
diff --git a/include/spi/spi.h b/include/spi/spi.h
index 53d6bd32e025..8363e73c6754 100644
--- a/include/spi/spi.h
+++ b/include/spi/spi.h
@@ -13,6 +13,19 @@
 struct spi_controller_mem_ops;
 struct spi_message;
 
+/**
+ * struct spi_delay - SPI delay information
+ * @value: Value for the delay
+ * @unit: Unit for the delay
+ */
+struct spi_delay {
+#define SPI_DELAY_UNIT_USECS	0
+#define SPI_DELAY_UNIT_NSECS	1
+#define SPI_DELAY_UNIT_SCK	2
+	u16	value;
+	u8	unit;
+};
+
 struct spi_board_info {
 	char	*name;
 	int	max_speed_hz;
@@ -26,6 +39,11 @@ struct spi_board_info {
 	u8	bits_per_word;
 	void	*platform_data;
 	struct device_node *device_node;
+
+	/* CS delays */
+	struct spi_delay	cs_setup;
+	struct spi_delay	cs_hold;
+	struct spi_delay	cs_inactive;
 };
 
 /**
@@ -101,6 +119,10 @@ struct spi_device {
 	void			*controller_data;
 	const char		*modalias;
 	struct gpio_desc	*cs_gpiod;	/* Chip select gpio desc */
+	/* CS delays */
+	struct spi_delay	cs_setup;
+	struct spi_delay	cs_hold;
+	struct spi_delay	cs_inactive;
 
 	/*
 	 * likely need more hooks for more protocol options affecting how
-- 
2.39.5