From 22de4391bc6b69c42ebf7c0a380e566d17810f0f Mon Sep 17 00:00:00 2001
From: Jernej Skrabec <jernej.skrabec@siol.net>
Date: Fri, 16 Aug 2019 16:38:21 +0200
Subject: mfd: Add support for X-Powers AC200

The X-Powers AC200 is a mixed signal multi-purpose chip, which provides
audio DAC/ADCs, a CVBS video encoder, a 100Mbit/s Ethernet PHY and a
real-time clock. Its control registers can be accessed via I2C or
Allwinner's RSB bus.
Beside this chip being used on some older boards (for instance the Remix
Mini PC), it is quite wide spread due to its die being co-packaged on the
Allwinner H6 and H616 SoCs, which use its audio, video and PHY
functionality.

Aside from the RTC, the other functions do not need constant
hand-holding via the I2C registers, but rather need to be configured and
enabled only once.

We model the control side of this chip using the MFD subsystem. This
driver here just provides the parent device for the various subfunctions,
and takes care of enabling clocks and reset, but also provides the regmap,
which the respective child drivers will use.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/mfd/Kconfig  |  12 +++
 drivers/mfd/Makefile |   1 +
 drivers/mfd/ac200.c  | 190 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 203 insertions(+)
 create mode 100644 drivers/mfd/ac200.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index ae23b317a64e..85f0eb5f764e 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -203,6 +203,18 @@ config MFD_AC100
 	  This driver include only the core APIs. You have to select individual
 	  components like codecs or RTC under the corresponding menus.
 
+config MFD_AC200
+	tristate "X-Powers AC200"
+	select MFD_CORE
+	select REGMAP_I2C
+	depends on COMMON_CLK
+	depends on I2C
+	depends on OF
+	help
+	  If you say Y here you get support for the X-Powers AC200 IC.
+	  This driver include only the core APIs. You have to select individual
+	  components like Ethernet PHY or codec under the corresponding menus.
+
 config MFD_AXP20X
 	tristate
 	select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index e057d6d6faef..03244b2c7306 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -146,6 +146,7 @@ obj-$(CONFIG_MFD_DA9052_SPI)	+= da9052-spi.o
 obj-$(CONFIG_MFD_DA9052_I2C)	+= da9052-i2c.o
 
 obj-$(CONFIG_MFD_AC100)		+= ac100.o
+obj-$(CONFIG_MFD_AC200)		+= ac200.o
 obj-$(CONFIG_MFD_AXP20X)	+= axp20x.o
 obj-$(CONFIG_MFD_AXP20X_I2C)	+= axp20x-i2c.o
 obj-$(CONFIG_MFD_AXP20X_RSB)	+= axp20x-rsb.o
diff --git a/drivers/mfd/ac200.c b/drivers/mfd/ac200.c
new file mode 100644
index 000000000000..ad28c380c880
--- /dev/null
+++ b/drivers/mfd/ac200.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MFD core driver for X-Powers' AC200 IC
+ *
+ * The AC200 is a chip which is co-packaged with Allwinner H6 SoC and
+ * includes analog audio codec, analog TV encoder, ethernet PHY, eFuse
+ * and RTC.
+ *
+ * Copyright (c) 2019 Jernej Skrabec <jernej.skrabec@gmail.com>
+ *
+ * Based on AC100 driver with following copyrights:
+ * Copyright (2016) Chen-Yu Tsai
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+struct ac200_dev {
+	struct clk	*clk;
+	struct regmap	*regmap;
+};
+
+#define AC200_SYS_CONTROL	0x0002
+#define AC200_SYS_BG_CTL	0x0050
+
+/* interface register (can be accessed from any page) */
+#define AC200_TWI_REG_ADDR_H	0xFE
+
+#define AC200_MAX_REG		0xA1F2
+
+static const struct regmap_range_cfg ac200_range_cfg[] = {
+	{
+		.range_max = AC200_MAX_REG,
+		.selector_reg = AC200_TWI_REG_ADDR_H,
+		.selector_mask = 0xff,
+		.selector_shift = 0,
+		.window_start = 0,
+		.window_len = 256,
+	}
+};
+
+static const struct regmap_config ac200_regmap_config = {
+	.name		= "AC200",
+	.reg_bits	= 8,
+	.reg_stride	= 2,
+	.val_bits	= 16,
+	.ranges		= ac200_range_cfg,
+	.num_ranges	= ARRAY_SIZE(ac200_range_cfg),
+	.max_register	= AC200_MAX_REG,
+};
+
+static struct mfd_cell ac200_cells[] = {
+	{
+		.name		= "ac200-codec",
+		.of_compatible	= "x-powers,ac200-codec",
+	}, {
+		.name		= "ac200-ephy-ctl",
+		.of_compatible	= "x-powers,ac200-ephy-ctl",
+	},
+};
+
+static int ac200_i2c_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct nvmem_cell *bgcell;
+	struct ac200_dev *ac200;
+	u16 *bgdata, bgval;
+	size_t bglen;
+	int ret;
+
+	ac200 = devm_kzalloc(dev, sizeof(*ac200), GFP_KERNEL);
+	if (!ac200)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, ac200);
+
+	ac200->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(ac200->clk))
+		return dev_err_probe(dev, PTR_ERR(ac200->clk),
+				     "Can't obtain the clock\n");
+
+	ac200->regmap = devm_regmap_init_i2c(i2c, &ac200_regmap_config);
+	if (IS_ERR(ac200->regmap)) {
+		ret = PTR_ERR(ac200->regmap);
+		dev_err(dev, "Regmap init failed: %d\n", ret);
+		return ret;
+	}
+
+	bgcell = devm_nvmem_cell_get(dev, "bandgap");
+	if (IS_ERR(bgcell))
+		return dev_err_probe(dev, PTR_ERR(bgcell),
+				     "Unable to find bandgap data!\n");
+
+	bgdata = nvmem_cell_read(bgcell, &bglen);
+	if (IS_ERR(bgdata)) {
+		dev_err(dev, "Unable to read bandgap data!\n");
+		return PTR_ERR(bgdata);
+	}
+
+	if (bglen != 2) {
+		dev_err(dev, "Invalid nvmem bandgap length!\n");
+		kfree(bgdata);
+		return -EINVAL;
+	}
+
+	bgval = *bgdata;
+	kfree(bgdata);
+
+	ret = clk_prepare_enable(ac200->clk);
+	if (ret)
+		return ret;
+
+	/*
+	 * There is no documentation on how long we have to wait before
+	 * executing first operation. Vendor driver sleeps for 40 ms.
+	 */
+	msleep(40);
+
+	ret = regmap_write(ac200->regmap, AC200_SYS_CONTROL, 0);
+	if (ret)
+		goto err;
+
+	ret = regmap_write(ac200->regmap, AC200_SYS_CONTROL, 1);
+	if (ret)
+		goto err;
+
+	if (bgval) {
+		/* bandgap register is not documented */
+		ret = regmap_write(ac200->regmap, AC200_SYS_BG_CTL,
+				   0x8280 | bgval);
+		if (ret)
+			goto err;
+	}
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE, ac200_cells,
+				   ARRAY_SIZE(ac200_cells), NULL, 0, NULL);
+	if (ret) {
+		dev_err(dev, "Failed to add MFD devices: %d\n", ret);
+		goto err;
+	}
+
+	return 0;
+
+err:
+	clk_disable_unprepare(ac200->clk);
+	return ret;
+}
+
+static void ac200_i2c_remove(struct i2c_client *i2c)
+{
+	struct ac200_dev *ac200 = i2c_get_clientdata(i2c);
+
+	regmap_write(ac200->regmap, AC200_SYS_CONTROL, 0);
+
+	clk_disable_unprepare(ac200->clk);
+}
+
+static const struct i2c_device_id ac200_ids[] = {
+	{ "ac200", },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ac200_ids);
+
+static const struct of_device_id ac200_of_match[] = {
+	{ .compatible = "x-powers,ac200" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ac200_of_match);
+
+static struct i2c_driver ac200_i2c_driver = {
+	.driver = {
+		.name	= "ac200",
+		.of_match_table	= of_match_ptr(ac200_of_match),
+	},
+	.probe	= ac200_i2c_probe,
+	.remove = ac200_i2c_remove,
+	.id_table = ac200_ids,
+};
+module_i2c_driver(ac200_i2c_driver);
+
+MODULE_DESCRIPTION("MFD core driver for AC200");
+MODULE_AUTHOR("Jernej Skrabec <jernej.skrabec@gmail.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.35.3

