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>

3 files changed, 251 insertions, 0 deletions

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index df33b8e2b5ad..bace9e98f75d 100644
--- a/drivers/clk/Kconfig
+++ b/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
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index d561825a87fc..6327536b4900 100644
--- a/drivers/clk/Makefile
+++ b/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
diff --git a/drivers/clk/clk-max77686.c b/drivers/clk/clk-max77686.c
new file mode 100644
index 000000000000..ac5f5434cb9a
--- /dev/null
+++ b/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");