[PATCH lora-next v2 7/8] net: lora: sx1301: add initial registration for regmap

[Ben Whitten <ben.whitten@gmail.com>]

The register and bit-field definitions are taken from the SX1301
datasheet version 2.01 dated June 2014 with the revision information
'First released version'.

The reset state and RW capability of each field is not reflected in this
patch however from the datasheet:
"Bits and registers that are not documented are reserved. They may
include calibration values. It is important not to modify these bits and
registers. If specific bits must be changed in a register with reserved
bits, the register must be read first, specific bits modified while
masking reserved bits and then the register can be written."

Then goes on to state:
"Reserved bits should be written with their reset state, they may be
read different states."

Caching is currently disabled.

The version is read back using regmap_read to verify regmap operation,
in doing so needs to be moved after priv and regmap allocation.

Further registers or fields are added as they are required in conversion.

Signed-off-by: Ben Whitten <ben.whitten@lairdtech.com>
---
 drivers/net/lora/Kconfig  |  1 +
 drivers/net/lora/sx1301.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
 drivers/net/lora/sx1301.h | 10 ++++++++++
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/drivers/net/lora/Kconfig b/drivers/net/lora/Kconfig
index bb57a01..79d23f2 100644
--- a/drivers/net/lora/Kconfig
+++ b/drivers/net/lora/Kconfig
@@ -49,6 +49,7 @@ config LORA_SX1301
 	tristate "Semtech SX1301 SPI driver"
 	default y
 	depends on SPI
+	select REGMAP_SPI
 	help
 	  Semtech SX1301
 
diff --git a/drivers/net/lora/sx1301.c b/drivers/net/lora/sx1301.c
index 8e81179..766df06 100644
--- a/drivers/net/lora/sx1301.c
+++ b/drivers/net/lora/sx1301.c
@@ -20,11 +20,11 @@
 #include <linux/of_gpio.h>
 #include <linux/lora/dev.h>
 #include <linux/spi/spi.h>
+#include <linux/regmap.h>
 
 #include "sx1301.h"
 
 #define REG_PAGE_RESET			0
-#define REG_VERSION			1
 #define REG_MCU_PROM_ADDR		9
 #define REG_MCU_PROM_DATA		10
 #define REG_GPIO_SELECT_INPUT		27
@@ -68,6 +68,35 @@
 
 #define REG_EMERGENCY_FORCE_HOST_CTRL	BIT(0)
 
+static const struct regmap_range_cfg sx1301_ranges[] = {
+	{
+		.name = "Pages",
+
+		.range_min = SX1301_VIRT_BASE,
+		.range_max = SX1301_MAX_REGISTER,
+
+		.selector_reg = SX1301_PAGE,
+		.selector_mask = 0x3,
+
+		.window_start = 0,
+		.window_len = SX1301_PAGE_LEN,
+	},
+};
+
+static struct regmap_config sx1301_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.cache_type = REGCACHE_NONE,
+
+	.read_flag_mask = 0,
+	.write_flag_mask = BIT(7),
+
+	.ranges = sx1301_ranges,
+	.num_ranges = ARRAY_SIZE(sx1301_ranges),
+	.max_register = SX1301_MAX_REGISTER,
+};
+
 struct spi_sx1301 {
 	struct spi_device *parent;
 	u8 page;
@@ -81,6 +110,7 @@ struct sx1301_priv {
 	struct gpio_desc *rst_gpio;
 	u8 cur_page;
 	struct spi_controller *radio_a_ctrl, *radio_b_ctrl;
+	struct regmap		*regmap;
 };
 
 static int sx1301_read_burst(struct sx1301_priv *priv, u8 reg, u8 *val, size_t len)
@@ -614,6 +644,7 @@ static int sx1301_probe(struct spi_device *spi)
 	struct spi_sx1301 *radio;
 	struct gpio_desc *rst;
 	int ret;
+	unsigned int ver;
 	u8 val;
 
 	rst = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_LOW);
@@ -641,14 +672,21 @@ static int sx1301_probe(struct spi_device *spi)
 	priv->spi = spi;
 	SET_NETDEV_DEV(netdev, &spi->dev);
 
-	ret = sx1301_read(priv, REG_VERSION, &val);
+	priv->regmap = devm_regmap_init_spi(spi, &sx1301_regmap_config);
+	if (IS_ERR(priv->regmap)) {
+		ret = PTR_ERR(priv->regmap);
+		dev_err(&spi->dev, "Regmap allocation failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_read(priv->regmap, SX1301_VER, &ver);
 	if (ret) {
 		dev_err(&spi->dev, "version read failed\n");
 		return ret;
 	}
 
-	if (val != SX1301_CHIP_VERSION) {
-		dev_err(&spi->dev, "unexpected version: %u\n", val);
+	if (ver != SX1301_CHIP_VERSION) {
+		dev_err(&spi->dev, "unexpected version: %u\n", ver);
 		return -ENXIO;
 	}
 
diff --git a/drivers/net/lora/sx1301.h b/drivers/net/lora/sx1301.h
index b37ac56..2fc283f 100644
--- a/drivers/net/lora/sx1301.h
+++ b/drivers/net/lora/sx1301.h
@@ -15,4 +15,14 @@
 #define SX1301_MCU_AGC_FW_VERSION 4
 #define SX1301_MCU_AGC_CAL_FW_VERSION 2
 
+/* Page independent */
+#define SX1301_PAGE     0x00
+#define SX1301_VER      0x01
+
+#define SX1301_VIRT_BASE    0x100
+#define SX1301_PAGE_LEN     0x80
+#define SX1301_PAGE_BASE(n) (SX1301_VIRT_BASE + (SX1301_PAGE_LEN * n))
+
+#define SX1301_MAX_REGISTER         (SX1301_PAGE_BASE(3) + 0x7F)
+
 #endif
-- 
2.7.4