[PATCH 2/2] clk: max77620: Add clock driver for MAX77620/MAX20024

[Laxman Dewangan <ldewangan@nvidia.com>]

MAXIM MAX77620 is the power management IC with multiple DCDC/LDO
regulators, RTC, GPIOs, Watchdog, 32KHz clock source etc.

Add support for controlling the 32KHz clock source via clock
framework.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
---
 drivers/clk/Kconfig        |   9 +++
 drivers/clk/Makefile       |   1 +
 drivers/clk/clk-max77620.c | 143 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 153 insertions(+)
 create mode 100644 drivers/clk/clk-max77620.c

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 98efbfc..149f813 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -34,6 +34,15 @@ source "drivers/clk/versatile/Kconfig"
 config COMMON_CLK_MAX_GEN
         bool
 
+config COMMON_CLK_MAX77620
+	tristate "Clock driver for Maxim 77620/MAX20024 MFD"
+	depends on MFD_MAX77620
+	---help---
+	  This driver supports Maxim MAX77620/MAX20024 32KHz crystal
+	  oscillator. These multi-function devices have one fixed rate.
+	  The clock can be ON and OFF. Say y to make this driver as
+	  built-in and m to make it as module.
+
 config COMMON_CLK_MAX77686
 	tristate "Clock driver for Maxim 77686 MFD"
 	depends on MFD_MAX77686
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index dcc5e69..8c2de43 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_ARCH_CLPS711X)		+= clk-clps711x.o
 obj-$(CONFIG_ARCH_EFM32)		+= clk-efm32gg.o
 obj-$(CONFIG_ARCH_HIGHBANK)		+= clk-highbank.o
 obj-$(CONFIG_MACH_LOONGSON32)		+= clk-ls1x.o
+obj-$(CONFIG_COMMON_CLK_MAX77620)	+= clk-max77620.o
 obj-$(CONFIG_COMMON_CLK_MAX_GEN)	+= clk-max-gen.o
 obj-$(CONFIG_COMMON_CLK_MAX77686)	+= clk-max77686.o
 obj-$(CONFIG_COMMON_CLK_MAX77802)	+= clk-max77802.o
diff --git a/drivers/clk/clk-max77620.c b/drivers/clk/clk-max77620.c
new file mode 100644
index 0000000..615cf2e
--- /dev/null
+++ b/drivers/clk/clk-max77620.c
@@ -0,0 +1,143 @@
+/*
+ * Clock driver for Maxim Max77620 device.
+ *
+ * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/mfd/max77620.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct max77620_clks_info {
+	struct device *dev;
+	struct regmap *rmap;
+	struct clk *clk;
+	struct clk_hw hw;
+};
+
+static struct max77620_clks_info *to_max77620_clks_info(struct clk_hw *hw)
+{
+	return container_of(hw, struct max77620_clks_info, hw);
+}
+
+static unsigned long max77620_clks_recalc_rate(struct clk_hw *hw,
+					       unsigned long parent_rate)
+{
+	return 32768;
+}
+
+static int max77620_clks_prepare(struct clk_hw *hw)
+{
+	struct max77620_clks_info *mci = to_max77620_clks_info(hw);
+
+	return regmap_update_bits(mci->rmap, MAX77620_REG_CNFG1_32K,
+				  MAX77620_CNFG1_32K_OUT0_EN,
+				  MAX77620_CNFG1_32K_OUT0_EN);
+}
+
+static void max77620_clks_unprepare(struct clk_hw *hw)
+{
+	struct max77620_clks_info *mci = to_max77620_clks_info(hw);
+
+	regmap_update_bits(mci->rmap, MAX77620_REG_CNFG1_32K,
+			   MAX77620_CNFG1_32K_OUT0_EN, 0);
+}
+
+static int max77620_clks_is_prepared(struct clk_hw *hw)
+{
+	struct max77620_clks_info *mci = to_max77620_clks_info(hw);
+	unsigned int rval;
+	int ret;
+
+	ret = regmap_read(mci->rmap, MAX77620_REG_CNFG1_32K, &rval);
+	if (ret < 0)
+		return ret;
+
+	return !!(rval & MAX77620_CNFG1_32K_OUT0_EN);
+}
+
+static struct clk_ops max77620_clks_ops = {
+	.prepare	= max77620_clks_prepare,
+	.unprepare	= max77620_clks_unprepare,
+	.is_prepared	= max77620_clks_is_prepared,
+	.recalc_rate	= max77620_clks_recalc_rate,
+};
+
+struct clk_init_data max77620_clk_init_data = {
+	.name = "clk-32k",
+	.ops = &max77620_clks_ops,
+	.flags = CLK_IGNORE_UNUSED,
+};
+
+static int max77620_clks_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.parent->of_node;
+	struct max77620_clks_info *mci;
+	struct clk *clk;
+	int ret;
+
+	mci = devm_kzalloc(&pdev->dev, sizeof(*mci), GFP_KERNEL);
+	if (!mci)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, mci);
+
+	mci->dev = &pdev->dev;
+	mci->rmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!mci->rmap) {
+		dev_err(mci->dev, "Failed to get parent regmap\n");
+		return -ENODEV;
+	}
+	mci->hw.init = &max77620_clk_init_data;
+
+	clk = devm_clk_register(&pdev->dev, &mci->hw);
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		dev_err(mci->dev, "Fail to register clock: %d\n", ret);
+		return ret;
+	}
+
+	mci->clk = clk;
+	ret = of_clk_add_provider(np, of_clk_src_simple_get, mci->clk);
+	if (ret < 0)
+		dev_err(&pdev->dev, "Fail to add clock driver, %d\n", ret);
+
+	return ret;
+}
+
+static int max77620_clks_remove(struct platform_device *pdev)
+{
+	of_clk_del_provider(pdev->dev.parent->of_node);
+
+	return 0;
+}
+
+static struct platform_device_id max77620_clks_devtype[] = {
+	{ .name = "max77620-clock", },
+	{},
+};
+
+static struct platform_driver max77620_clks_driver = {
+	.driver = {
+		.name = "max77620-clock",
+	},
+	.probe = max77620_clks_probe,
+	.remove = max77620_clks_remove,
+	.id_table = max77620_clks_devtype,
+};
+
+module_platform_driver(max77620_clks_driver);
+
+MODULE_DESCRIPTION("Clock driver for Maxim max77620 PMIC Device");
+MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4