gpio/mpc83xx_spisel_boot.c: gpio driver for SPISEL_BOOT signal

Some SoCs in the mpc83xx family, e.g. mpc8309, have a dedicated spi
chip select, SPISEL_BOOT, that is used by the boot code to boot from
flash.

This chip select will typically be used to select a SPI boot
flash. The SPISEL_BOOT signal is controlled by a single bit in the
SPI_CS register.

Implement a gpio driver for the spi chip select register. This allows a
spi driver capable of using gpios as chip select, to bind a chip select
to SPISEL_BOOT.

It may be a little odd to do this as a GPIO driver, since the signal
is neither GP or I, but it is quite convenient to present it to the
spi driver that way. The alternative it to teach mpc8xxx_spi to handle
the SPISEL_BOOT signal itself (that is how it's done in the linux
kernel, see commit 69b921acae8a)

Signed-off-by: Klaus H. Sorensen <khso@prevas.dk>
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>

doc/device-tree-bindings/gpio/fsl,mpc83xx-spisel-boot.txt

@@ -0,0 +1,22 @@
+MPC83xx SPISEL_BOOT gpio controller
+
+Provide access to MPC83xx SPISEL_BOOT signal as a gpio to allow it to be
+easily bound as a SPI controller chip select.
+
+The SPISEL_BOOT signal is always an output.
+
+Required properties:
+
+- compatible: must be "fsl,mpc83xx-spisel-boot" or "fsl,mpc8309-spisel-boot".
+- reg: must point to the SPI_CS register in the SoC register map.
+- ngpios: number of gpios provided by driver, normally 1.
+
+Example:
+
+	spisel_boot: spisel_boot@14c {
+		compatible = "fsl,mpc8309-spisel-boot";
+		reg = <0x14c 0x04>;
+		#gpio-cells = <2>;
+		device_type = "gpio";
+		ngpios = <1>;
+	};

drivers/gpio/Kconfig

@@ -423,6 +423,14 @@ config MPC8XXX_GPIO
 	  value setting, the open-drain feature, which can configure individual
 	  GPIOs to work as open-drain outputs, is supported.
 
+config MPC83XX_SPISEL_BOOT
+	bool "Freescale MPC83XX SPISEL_BOOT driver"
+	depends on DM_GPIO && ARCH_MPC830X
+	help
+	  GPIO driver to set/clear dedicated SPISEL_BOOT output on MPC83XX.
+
+	  This pin is typically used as spi chip select to a spi nor flash.
+
 config MT7621_GPIO
 	bool "MediaTek MT7621 GPIO driver"
 	depends on DM_GPIO && SOC_MT7628

drivers/gpio/Makefile

@@ -40,6 +40,7 @@ obj-$(CONFIG_DM644X_GPIO)	+= da8xx_gpio.o
 obj-$(CONFIG_ALTERA_PIO)	+= altera_pio.o
 obj-$(CONFIG_MPC83XX_GPIO)	+= mpc83xx_gpio.o
 obj-$(CONFIG_MPC8XXX_GPIO)	+= mpc8xxx_gpio.o
+obj-$(CONFIG_MPC83XX_SPISEL_BOOT)	+= mpc83xx_spisel_boot.o
 obj-$(CONFIG_SH_GPIO_PFC)	+= sh_pfc.o
 obj-$(CONFIG_OMAP_GPIO)	+= omap_gpio.o
 obj-$(CONFIG_DB8500_GPIO)	+= db8500_gpio.o

drivers/gpio/mpc83xx_spisel_boot.c

@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2019 DEIF A/S
+ *
+ * GPIO driver to set/clear SPISEL_BOOT pin on mpc83xx.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <mapmem.h>
+#include <asm/gpio.h>
+
+struct mpc83xx_spisel_boot {
+	u32 __iomem *spi_cs;
+	ulong addr;
+	uint gpio_count;
+	ulong type;
+};
+
+static u32 gpio_mask(uint gpio)
+{
+	return (1U << (31 - (gpio)));
+}
+
+static int mpc83xx_spisel_boot_direction_input(struct udevice *dev, uint gpio)
+{
+	return -EINVAL;
+}
+
+static int mpc83xx_spisel_boot_set_value(struct udevice *dev, uint gpio, int value)
+{
+	struct mpc83xx_spisel_boot *data = dev_get_priv(dev);
+
+	debug("%s: gpio=%d, value=%u, gpio_mask=0x%08x\n", __func__,
+	      gpio, value, gpio_mask(gpio));
+
+	if (value)
+		setbits_be32(data->spi_cs, gpio_mask(gpio));
+	else
+		clrbits_be32(data->spi_cs, gpio_mask(gpio));
+
+	return 0;
+}
+
+static int mpc83xx_spisel_boot_direction_output(struct udevice *dev, uint gpio, int value)
+{
+	return 0;
+}
+
+static int mpc83xx_spisel_boot_get_value(struct udevice *dev, uint gpio)
+{
+	struct mpc83xx_spisel_boot *data = dev_get_priv(dev);
+
+	return !!(in_be32(data->spi_cs) & gpio_mask(gpio));
+}
+
+static int mpc83xx_spisel_boot_get_function(struct udevice *dev, uint gpio)
+{
+	return GPIOF_OUTPUT;
+}
+
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+static int mpc83xx_spisel_boot_ofdata_to_platdata(struct udevice *dev)
+{
+	struct mpc8xxx_gpio_plat *plat = dev_get_platdata(dev);
+	fdt_addr_t addr;
+	u32 reg[2];
+
+	dev_read_u32_array(dev, "reg", reg, 2);
+	addr = dev_translate_address(dev, reg);
+
+	plat->addr = addr;
+	plat->size = reg[1];
+	plat->ngpios = dev_read_u32_default(dev, "ngpios", 1);
+
+	return 0;
+}
+#endif
+
+static int mpc83xx_spisel_boot_platdata_to_priv(struct udevice *dev)
+{
+	struct mpc83xx_spisel_boot *priv = dev_get_priv(dev);
+	struct mpc8xxx_gpio_plat *plat = dev_get_platdata(dev);
+	unsigned long size = plat->size;
+	ulong driver_data = dev_get_driver_data(dev);
+
+	if (size == 0)
+		size = 0x04;
+
+	priv->addr = plat->addr;
+	priv->spi_cs = map_sysmem(plat->addr, size);
+
+	if (!priv->spi_cs)
+		return -ENOMEM;
+
+	priv->gpio_count = plat->ngpios;
+
+	priv->type = driver_data;
+
+	return 0;
+}
+
+static int mpc83xx_spisel_boot_probe(struct udevice *dev)
+{
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+	struct mpc83xx_spisel_boot *data = dev_get_priv(dev);
+	char name[32], *str;
+
+	mpc83xx_spisel_boot_platdata_to_priv(dev);
+
+	snprintf(name, sizeof(name), "MPC@%lx_", data->addr);
+	str = strdup(name);
+
+	if (!str)
+		return -ENOMEM;
+
+	uc_priv->bank_name = str;
+	uc_priv->gpio_count = data->gpio_count;
+
+	return 0;
+}
+
+static const struct dm_gpio_ops mpc83xx_spisel_boot_ops = {
+	.direction_input	= mpc83xx_spisel_boot_direction_input,
+	.direction_output	= mpc83xx_spisel_boot_direction_output,
+	.get_value		= mpc83xx_spisel_boot_get_value,
+	.set_value		= mpc83xx_spisel_boot_set_value,
+	.get_function		= mpc83xx_spisel_boot_get_function,
+};
+
+static const struct udevice_id mpc83xx_spisel_boot_ids[] = {
+	{ .compatible = "fsl,mpc8309-spisel-boot" },
+	{ .compatible = "fsl,mpc83xx-spisel-boot" },
+	{ /* sentinel */ }
+};
+
+U_BOOT_DRIVER(spisel_boot_mpc83xx) = {
+	.name	= "spisel_boot_mpc83xx",
+	.id	= UCLASS_GPIO,
+	.ops	= &mpc83xx_spisel_boot_ops,
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+	.ofdata_to_platdata = mpc83xx_spisel_boot_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct mpc8xxx_gpio_plat),
+	.of_match = mpc83xx_spisel_boot_ids,
+#endif
+	.probe	= mpc83xx_spisel_boot_probe,
+	.priv_auto_alloc_size = sizeof(struct mpc83xx_spisel_boot),
+};