clock: max77686: Add driver for Maxim 77686 32Khz crystal oscillator.

This patch supports max77686 mfd's clock driver using common clock frame work.
max77686 has 3 clock ouputs which all are generated from crystal oscillator and
SOC can enable/disable them via I2C bus. All clocks are fixed-rate clock sources
so that it doesn't supply interface for changing clock rate.
Driver uses regmap API to communicate with internal register.

Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/Kconfig

@@ -47,4 +47,10 @@ config COMMON_CLK_VERSATILE
           Supports clocking on ARM Reference designs Integrator/AP,
 	  Integrator/CP, RealView PB1176, EB, PB11MP and PBX.
 
+config COMMON_CLK_MAX77686
+	tristate "Clock driver for Maxim 77686 MFD"
+	depends on MFD_MAX77686
+	---help---
+	  This driver supports Maxim 77686 crystal oscillator clock. 
+
 endmenu

drivers/clk/Makefile

@@ -19,3 +19,4 @@ obj-$(CONFIG_ARCH_U8500)	+= ux500/
 
 # Chip specific
 obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
+obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o

drivers/clk/clk-max77686.c

@@ -0,0 +1,244 @@
+/*
+ * clk-max77686.c - Clock driver for Maxim 77686
+ *
+ * Copyright (C) 2012 Samsung Electornics
+ * Jonghwa Lee <jonghwa3.lee@samsung.com>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/max77686.h>
+#include <linux/mfd/max77686-private.h>
+#include <linux/clk-provider.h>
+#include <linux/mutex.h>
+#include <linux/clkdev.h>
+
+enum {
+	MAX77686_CLK_AP = 0,
+	MAX77686_CLK_CP,
+	MAX77686_CLK_PMIC,
+	MAX77686_CLKS_NUM,
+};
+
+struct max77686_clk {
+	struct max77686_dev *iodev;
+	u32 mask;
+	struct clk_hw hw;
+	struct clk_lookup *lookup;
+};
+
+static struct max77686_clk *get_max77686_clk(struct clk_hw *hw)
+{
+	return container_of(hw, struct max77686_clk, hw);
+}
+
+static int max77686_clk_prepare(struct clk_hw *hw)
+{
+	struct max77686_clk *max77686;
+	int ret;
+
+	max77686 = get_max77686_clk(hw);
+	if (!max77686)
+		return -ENOMEM;
+
+	ret = regmap_update_bits(max77686->iodev->regmap,
+		MAX77686_REG_32KHZ, max77686->mask, max77686->mask);
+
+	return ret;
+}
+
+static void max77686_clk_unprepare(struct clk_hw *hw)
+{
+	struct max77686_clk *max77686;
+
+	max77686 = get_max77686_clk(hw);
+	if (!max77686)
+		return;
+
+	regmap_update_bits(max77686->iodev->regmap,
+		MAX77686_REG_32KHZ, max77686->mask, ~max77686->mask);
+}
+
+static int max77686_clk_is_enabled(struct clk_hw *hw)
+{
+	struct max77686_clk *max77686;
+	int ret;
+	u32 val;
+
+	max77686 = get_max77686_clk(hw);
+	if (!max77686)
+		return -ENOMEM;
+
+	ret = regmap_read(max77686->iodev->regmap,
+				MAX77686_REG_32KHZ, &val);
+
+	if (ret < 0)
+		return -EINVAL;
+
+	return val & max77686->mask;
+}
+
+static struct clk_ops max77686_clk_ops = {
+	.prepare	= max77686_clk_prepare,
+	.unprepare	= max77686_clk_unprepare,
+	.is_enabled	= max77686_clk_is_enabled,
+};
+
+static struct clk_init_data max77686_clks_init[MAX77686_CLKS_NUM] = {
+	[MAX77686_CLK_AP] = {
+		.name = "32khz_ap",
+		.ops = &max77686_clk_ops,
+		.flags = CLK_IS_ROOT,
+	},
+	[MAX77686_CLK_CP] = {
+		.name = "32khz_cp",
+		.ops = &max77686_clk_ops,
+		.flags = CLK_IS_ROOT,
+	},
+	[MAX77686_CLK_PMIC] = {
+		.name = "32khz_pmic",
+		.ops = &max77686_clk_ops,
+		.flags = CLK_IS_ROOT,
+	},
+};
+
+static int max77686_clk_register(struct device *dev,
+				struct max77686_clk *max77686)
+{
+	struct clk *clk;
+	struct clk_hw *hw = &max77686->hw;
+
+	clk = clk_register(dev, hw);
+
+	if (IS_ERR(clk))
+		return -ENOMEM;
+
+	max77686->lookup = devm_kzalloc(dev, sizeof(struct clk_lookup),
+					GFP_KERNEL);
+	if (IS_ERR(max77686->lookup))
+		return -ENOMEM;
+
+	max77686->lookup->con_id = hw->init->name;
+	max77686->lookup->clk = clk;
+
+	clkdev_add(max77686->lookup);
+
+	return 0;
+}
+
+static __devinit int max77686_clk_probe(struct platform_device *pdev)
+{
+	struct max77686_dev *iodev = dev_get_drvdata(pdev->dev.parent);
+	struct max77686_clk **max77686_clks;
+	int i, ret;
+
+	max77686_clks = devm_kzalloc(&pdev->dev, sizeof(struct max77686_clk *)
+					* MAX77686_CLKS_NUM, GFP_KERNEL);
+	if (IS_ERR(max77686_clks))
+		return -ENOMEM;
+
+	for (i = 0; i < MAX77686_CLKS_NUM; i++) {
+		max77686_clks[i] = devm_kzalloc(&pdev->dev,
+					sizeof(struct max77686_clk), GFP_KERNEL);
+		if (IS_ERR(max77686_clks[i]))
+			return -ENOMEM;
+	}
+
+	for (i = 0; i < MAX77686_CLKS_NUM; i++) {
+		max77686_clks[i]->iodev = iodev;
+		max77686_clks[i]->mask = 1 << i;
+		max77686_clks[i]->hw.init = &max77686_clks_init[i];
+
+		ret = max77686_clk_register(&pdev->dev, max77686_clks[i]);
+		if (ret) {
+			switch (i) {
+			case MAX77686_CLK_AP:
+				dev_err(&pdev->dev, "Fail to register CLK_AP\n");
+				goto err_clk_ap;
+				break;
+			case MAX77686_CLK_CP:
+				dev_err(&pdev->dev, "Fail to register CLK_CP\n");
+				goto err_clk_cp;
+				break;
+			case MAX77686_CLK_PMIC:
+				dev_err(&pdev->dev, "Fail to register CLK_PMIC\n");
+				goto err_clk_pmic;
+			}
+		}
+	}
+
+	platform_set_drvdata(pdev, max77686_clks);
+
+	goto out;
+
+err_clk_pmic:
+	clkdev_drop(max77686_clks[MAX77686_CLK_CP]->lookup);
+	kfree(max77686_clks[MAX77686_CLK_CP]->hw.clk);
+err_clk_cp:
+	clkdev_drop(max77686_clks[MAX77686_CLK_AP]->lookup);
+	kfree(max77686_clks[MAX77686_CLK_AP]->hw.clk);
+err_clk_ap:
+out:
+	return ret;
+}
+
+static int __devexit max77686_clk_remove(struct platform_device *pdev)
+{
+	struct max77686_clk **max77686_clks = platform_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < MAX77686_CLKS_NUM; i++) {
+		clkdev_drop(max77686_clks[i]->lookup);
+		kfree(max77686_clks[i]->hw.clk);
+	}
+	return 0;
+}
+
+static const struct platform_device_id max77686_clk_id[] = {
+	{ "max77686-clk", 0},
+	{ },
+};
+MODULE_DEVICE_TABLE(platform, max77686_clk_id);
+
+static struct platform_driver max77686_clk_driver = {
+	.driver = {
+		.name  = "max77686-clk",
+		.owner = THIS_MODULE,
+	},
+	.probe = max77686_clk_probe,
+	.remove = __devexit_p(max77686_clk_remove),
+	.id_table = max77686_clk_id,
+};
+
+static int __init max77686_clk_init(void)
+{
+	return platform_driver_register(&max77686_clk_driver);
+}
+subsys_initcall(max77686_clk_init);
+
+static void __init max77686_clk_cleanup(void)
+{
+	platform_driver_unregister(&max77686_clk_driver);
+}
+module_exit(max77686_clk_cleanup);
+
+MODULE_DESCRIPTION("MAXIM 77686 Clock Driver");
+MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>");
+MODULE_LICENSE("GPL");