mfd: Add support for the Khadas System control Microcontroller

This Microcontroller is present on the Khadas VIM1, VIM2, VIM3 and Edge
boards.

It has multiple boot control features like password check, power-on
options, power-off control and system FAN control on recent boards.

This implements a very basic MFD driver with the fan control and User
NVMEM cells.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -2053,6 +2053,27 @@ config MFD_WCD934X
 	  This driver provides common support WCD934x audio codec and its
 	  associated Pin Controller, Soundwire Controller and Audio codec.
 
+config MFD_KHADAS_MCU
+	tristate "Support for Khadas System control Microcontroller"
+	depends on I2C
+	depends on ARCH_MESON || ARCH_ROCKCHIP || COMPILE_TEST
+	select MFD_CORE
+	select REGMAP_I2C
+	help
+	  Support for the Khadas System control Microcontroller interface
+	  present on their VIM and Edge boards.
+
+	  This Microcontroller is present on the Khadas VIM1, VIM2, VIM3 and
+	  Edge boards.
+
+	  It provides multiple boot control features like password check,
+	  power-on options, power-off control and system FAN control on recent
+	  boards.
+
+	  This driver provides common support for accessing the device,
+	  additional drivers must be enabled in order to use the functionality
+	  of the device.
+
 menu "Multimedia Capabilities Port drivers"
 	depends on ARCH_SA1100
 

drivers/mfd/Makefile

@@ -262,5 +262,6 @@ obj-$(CONFIG_MFD_ROHM_BD70528)	+= rohm-bd70528.o
 obj-$(CONFIG_MFD_ROHM_BD71828)	+= rohm-bd71828.o
 obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o
 obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o
+obj-$(CONFIG_MFD_KHADAS_MCU) 	+= khadas-mcu.o
 
 obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o

drivers/mfd/khadas-mcu.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Khadas System control Microcontroller
+ *
+ * Copyright (C) 2020 BayLibre SAS
+ *
+ * Author(s): Neil Armstrong <narmstrong@baylibre.com>
+ */
+#include <linux/bitfield.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/khadas-mcu.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+static bool khadas_mcu_reg_volatile(struct device *dev, unsigned int reg)
+{
+	if (reg >= KHADAS_MCU_USER_DATA_0_REG &&
+	    reg < KHADAS_MCU_PWR_OFF_CMD_REG)
+		return true;
+
+	switch (reg) {
+	case KHADAS_MCU_PWR_OFF_CMD_REG:
+	case KHADAS_MCU_PASSWD_START_REG:
+	case KHADAS_MCU_CHECK_VEN_PASSWD_REG:
+	case KHADAS_MCU_CHECK_USER_PASSWD_REG:
+	case KHADAS_MCU_WOL_INIT_START_REG:
+	case KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool khadas_mcu_reg_writeable(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case KHADAS_MCU_PASSWD_VEN_0_REG:
+	case KHADAS_MCU_PASSWD_VEN_1_REG:
+	case KHADAS_MCU_PASSWD_VEN_2_REG:
+	case KHADAS_MCU_PASSWD_VEN_3_REG:
+	case KHADAS_MCU_PASSWD_VEN_4_REG:
+	case KHADAS_MCU_PASSWD_VEN_5_REG:
+	case KHADAS_MCU_MAC_0_REG:
+	case KHADAS_MCU_MAC_1_REG:
+	case KHADAS_MCU_MAC_2_REG:
+	case KHADAS_MCU_MAC_3_REG:
+	case KHADAS_MCU_MAC_4_REG:
+	case KHADAS_MCU_MAC_5_REG:
+	case KHADAS_MCU_USID_0_REG:
+	case KHADAS_MCU_USID_1_REG:
+	case KHADAS_MCU_USID_2_REG:
+	case KHADAS_MCU_USID_3_REG:
+	case KHADAS_MCU_USID_4_REG:
+	case KHADAS_MCU_USID_5_REG:
+	case KHADAS_MCU_VERSION_0_REG:
+	case KHADAS_MCU_VERSION_1_REG:
+	case KHADAS_MCU_DEVICE_NO_0_REG:
+	case KHADAS_MCU_DEVICE_NO_1_REG:
+	case KHADAS_MCU_FACTORY_TEST_REG:
+	case KHADAS_MCU_SHUTDOWN_NORMAL_STATUS_REG:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static const struct regmap_config khadas_mcu_regmap_config = {
+	.reg_bits	= 8,
+	.reg_stride	= 1,
+	.val_bits	= 8,
+	.max_register	= KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
+	.volatile_reg	= khadas_mcu_reg_volatile,
+	.writeable_reg	= khadas_mcu_reg_writeable,
+	.cache_type	= REGCACHE_RBTREE,
+};
+
+static struct mfd_cell khadas_mcu_fan_cells[] = {
+	/* VIM1/2 Rev13+ and VIM3 only */
+	{ .name = "khadas-mcu-fan-ctrl", },
+};
+
+static struct mfd_cell khadas_mcu_cells[] = {
+	{ .name = "khadas-mcu-user-mem", },
+};
+
+static int khadas_mcu_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct khadas_mcu *ddata;
+	int ret;
+
+	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, ddata);
+
+	ddata->dev = dev;
+
+	ddata->regmap = devm_regmap_init_i2c(client, &khadas_mcu_regmap_config);
+	if (IS_ERR(ddata->regmap)) {
+		ret = PTR_ERR(ddata->regmap);
+		dev_err(dev, "Failed to allocate register map: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				   khadas_mcu_cells,
+				   ARRAY_SIZE(khadas_mcu_cells),
+				   NULL, 0, NULL);
+	if (ret)
+		return ret;
+
+	if (of_find_property(dev->of_node, "#cooling-cells", NULL))
+		return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+					    khadas_mcu_fan_cells,
+					    ARRAY_SIZE(khadas_mcu_fan_cells),
+					    NULL, 0, NULL);
+
+	return 0;
+}
+
+static const struct of_device_id khadas_mcu_of_match[] = {
+	{ .compatible = "khadas,mcu", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, khadas_mcu_of_match);
+
+static struct i2c_driver khadas_mcu_driver = {
+	.driver = {
+		.name = "khadas-mcu-core",
+		.of_match_table = of_match_ptr(khadas_mcu_of_match),
+	},
+	.probe = khadas_mcu_probe,
+};
+module_i2c_driver(khadas_mcu_driver);
+
+MODULE_DESCRIPTION("Khadas MCU core driver");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
+MODULE_LICENSE("GPL v2");

include/linux/mfd/khadas-mcu.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Khadas System control Microcontroller Register map
+ *
+ * Copyright (C) 2020 BayLibre SAS
+ *
+ * Author(s): Neil Armstrong <narmstrong@baylibre.com>
+ */
+
+#ifndef MFD_KHADAS_MCU_H
+#define MFD_KHADAS_MCU_H
+
+#define KHADAS_MCU_PASSWD_VEN_0_REG		0x00 /* RO */
+#define KHADAS_MCU_PASSWD_VEN_1_REG		0x01 /* RO */
+#define KHADAS_MCU_PASSWD_VEN_2_REG		0x02 /* RO */
+#define KHADAS_MCU_PASSWD_VEN_3_REG		0x03 /* RO */
+#define KHADAS_MCU_PASSWD_VEN_4_REG		0x04 /* RO */
+#define KHADAS_MCU_PASSWD_VEN_5_REG		0x05 /* RO */
+#define KHADAS_MCU_MAC_0_REG			0x06 /* RO */
+#define KHADAS_MCU_MAC_1_REG			0x07 /* RO */
+#define KHADAS_MCU_MAC_2_REG			0x08 /* RO */
+#define KHADAS_MCU_MAC_3_REG			0x09 /* RO */
+#define KHADAS_MCU_MAC_4_REG			0x0a /* RO */
+#define KHADAS_MCU_MAC_5_REG			0x0b /* RO */
+#define KHADAS_MCU_USID_0_REG			0x0c /* RO */
+#define KHADAS_MCU_USID_1_REG			0x0d /* RO */
+#define KHADAS_MCU_USID_2_REG			0x0e /* RO */
+#define KHADAS_MCU_USID_3_REG			0x0f /* RO */
+#define KHADAS_MCU_USID_4_REG			0x10 /* RO */
+#define KHADAS_MCU_USID_5_REG			0x11 /* RO */
+#define KHADAS_MCU_VERSION_0_REG		0x12 /* RO */
+#define KHADAS_MCU_VERSION_1_REG		0x13 /* RO */
+#define KHADAS_MCU_DEVICE_NO_0_REG		0x14 /* RO */
+#define KHADAS_MCU_DEVICE_NO_1_REG		0x15 /* RO */
+#define KHADAS_MCU_FACTORY_TEST_REG		0x16 /* R */
+#define KHADAS_MCU_BOOT_MODE_REG		0x20 /* RW */
+#define KHADAS_MCU_BOOT_EN_WOL_REG		0x21 /* RW */
+#define KHADAS_MCU_BOOT_EN_RTC_REG		0x22 /* RW */
+#define KHADAS_MCU_BOOT_EN_EXP_REG		0x23 /* RW */
+#define KHADAS_MCU_BOOT_EN_IR_REG		0x24 /* RW */
+#define KHADAS_MCU_BOOT_EN_DCIN_REG		0x25 /* RW */
+#define KHADAS_MCU_BOOT_EN_KEY_REG		0x26 /* RW */
+#define KHADAS_MCU_KEY_MODE_REG			0x27 /* RW */
+#define KHADAS_MCU_LED_MODE_ON_REG		0x28 /* RW */
+#define KHADAS_MCU_LED_MODE_OFF_REG		0x29 /* RW */
+#define KHADAS_MCU_SHUTDOWN_NORMAL_REG		0x2c /* RW */
+#define KHADAS_MCU_MAC_SWITCH_REG		0x2d /* RW */
+#define KHADAS_MCU_MCU_SLEEP_MODE_REG		0x2e /* RW */
+#define KHADAS_MCU_IR_CODE1_0_REG		0x2f /* RW */
+#define KHADAS_MCU_IR_CODE1_1_REG		0x30 /* RW */
+#define KHADAS_MCU_IR_CODE1_2_REG		0x31 /* RW */
+#define KHADAS_MCU_IR_CODE1_3_REG		0x32 /* RW */
+#define KHADAS_MCU_USB_PCIE_SWITCH_REG		0x33 /* RW */
+#define KHADAS_MCU_IR_CODE2_0_REG		0x34 /* RW */
+#define KHADAS_MCU_IR_CODE2_1_REG		0x35 /* RW */
+#define KHADAS_MCU_IR_CODE2_2_REG		0x36 /* RW */
+#define KHADAS_MCU_IR_CODE2_3_REG		0x37 /* RW */
+#define KHADAS_MCU_PASSWD_USER_0_REG		0x40 /* RW */
+#define KHADAS_MCU_PASSWD_USER_1_REG		0x41 /* RW */
+#define KHADAS_MCU_PASSWD_USER_2_REG		0x42 /* RW */
+#define KHADAS_MCU_PASSWD_USER_3_REG		0x43 /* RW */
+#define KHADAS_MCU_PASSWD_USER_4_REG		0x44 /* RW */
+#define KHADAS_MCU_PASSWD_USER_5_REG		0x45 /* RW */
+#define KHADAS_MCU_USER_DATA_0_REG		0x46 /* RW 56 bytes */
+#define KHADAS_MCU_PWR_OFF_CMD_REG		0x80 /* WO */
+#define KHADAS_MCU_PASSWD_START_REG		0x81 /* WO */
+#define KHADAS_MCU_CHECK_VEN_PASSWD_REG		0x82 /* WO */
+#define KHADAS_MCU_CHECK_USER_PASSWD_REG	0x83 /* WO */
+#define KHADAS_MCU_SHUTDOWN_NORMAL_STATUS_REG	0x86 /* RO */
+#define KHADAS_MCU_WOL_INIT_START_REG		0x87 /* WO */
+#define KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG	0x88 /* WO */
+
+enum {
+	KHADAS_BOARD_VIM1 = 0x1,
+	KHADAS_BOARD_VIM2,
+	KHADAS_BOARD_VIM3,
+	KHADAS_BOARD_EDGE = 0x11,
+	KHADAS_BOARD_EDGE_V,
+};
+
+/**
+ * struct khadas_mcu - Khadas MCU structure
+ * @device:		device reference used for logs
+ * @regmap:		register map
+ */
+struct khadas_mcu {
+	struct device *dev;
+	struct regmap *regmap;
+};
+
+#endif /* MFD_KHADAS_MCU_H */