clk: x86: Add Atom PMC platform clocks

The BayTrail and CherryTrail platforms provide platform clocks
through their Power Management Controller (PMC).

The SoC supports up to 6 clocks (PMC_PLT_CLK[0..5]) with a
frequency of either 19.2 MHz (PLL) or 25 MHz (XTAL) for BayTrail
and a frequency of 19.2 MHz (XTAL) for CherryTrail. These clocks
are available for general system use, where appropriate, and each
have Control & Frequency register fields associated with them.

Port from legacy by Pierre Bossart, integration in clock framework
by Irina Tirdea

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

2 files changed, 372 insertions, 0 deletions

diff --git a/drivers/clk/x86/Makefile b/drivers/clk/x86/Makefile
index 04781389d0fb..1367afb03858 100644
--- a/drivers/clk/x86/Makefile
+++ b/drivers/clk/x86/Makefile
@@ -1,2 +1,3 @@
 clk-x86-lpss-objs               := clk-lpt.o
 obj-$(CONFIG_X86_INTEL_LPSS)    += clk-x86-lpss.o
+obj-$(CONFIG_PMC_ATOM)          += clk-pmc-atom.o
diff --git a/drivers/clk/x86/clk-pmc-atom.c b/drivers/clk/x86/clk-pmc-atom.c
new file mode 100644
index 000000000000..2b60577703ef
--- /dev/null
+++ b/drivers/clk/x86/clk-pmc-atom.c
@@ -0,0 +1,371 @@
+/*
+ * Intel Atom platform clocks driver for BayTrail and CherryTrail SoCs
+ *
+ * Copyright (C) 2016, Intel Corporation
+ * Author: Irina Tirdea <irina.tirdea@intel.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope 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.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/err.h>
+#include <linux/platform_data/x86/clk-pmc-atom.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define PLT_CLK_NAME_BASE       "pmc_plt_clk"
+
+#define PMC_CLK_CTL_OFFSET              0x60
+#define PMC_CLK_CTL_SIZE                4
+#define PMC_CLK_NUM                     6
+#define PMC_CLK_CTL_GATED_ON_D3         0x0
+#define PMC_CLK_CTL_FORCE_ON            0x1
+#define PMC_CLK_CTL_FORCE_OFF           0x2
+#define PMC_CLK_CTL_RESERVED            0x3
+#define PMC_MASK_CLK_CTL                GENMASK(1, 0)
+#define PMC_MASK_CLK_FREQ               BIT(2)
+#define PMC_CLK_FREQ_XTAL               (0 << 2)        /* 25 MHz */
+#define PMC_CLK_FREQ_PLL                (1 << 2)        /* 19.2 MHz */
+
+struct clk_plt_fixed {
+        struct clk_hw *clk;
+        struct clk_lookup *lookup;
+};
+
+struct clk_plt {
+        struct clk_hw hw;
+        void __iomem *reg;
+        struct clk_lookup *lookup;
+        /* protect access to PMC registers */
+        spinlock_t lock;
+};
+
+#define to_clk_plt(_hw) container_of(_hw, struct clk_plt, hw)
+
+struct clk_plt_data {
+        struct clk_plt_fixed **parents;
+        u8 nparents;
+        struct clk_plt *clks[PMC_CLK_NUM];
+};
+
+/* Return an index in parent table */
+static inline int plt_reg_to_parent(int reg)
+{
+        switch (reg & PMC_MASK_CLK_FREQ) {
+        default:
+        case PMC_CLK_FREQ_XTAL:
+                return 0;
+        case PMC_CLK_FREQ_PLL:
+                return 1;
+        }
+}
+
+/* Return clk index of parent */
+static inline int plt_parent_to_reg(int index)
+{
+        switch (index) {
+        default:
+        case 0:
+                return PMC_CLK_FREQ_XTAL;
+        case 1:
+                return PMC_CLK_FREQ_PLL;
+        }
+}
+
+/* Abstract status in simpler enabled/disabled value */
+static inline int plt_reg_to_enabled(int reg)
+{
+        switch (reg & PMC_MASK_CLK_CTL) {
+        case PMC_CLK_CTL_GATED_ON_D3:
+        case PMC_CLK_CTL_FORCE_ON:
+                return 1;       /* enabled */
+        case PMC_CLK_CTL_FORCE_OFF:
+        case PMC_CLK_CTL_RESERVED:
+        default:
+                return 0;       /* disabled */
+        }
+}
+
+static void plt_clk_reg_update(struct clk_plt *clk, u32 mask, u32 val)
+{
+        u32 tmp;
+        unsigned long flags;
+
+        spin_lock_irqsave(&clk->lock, flags);
+
+        tmp = readl(clk->reg);
+        tmp = (tmp & ~mask) | (val & mask);
+        writel(tmp, clk->reg);
+
+        spin_unlock_irqrestore(&clk->lock, flags);
+}
+
+static int plt_clk_set_parent(struct clk_hw *hw, u8 index)
+{
+        struct clk_plt *clk = to_clk_plt(hw);
+
+        plt_clk_reg_update(clk, PMC_MASK_CLK_FREQ, plt_parent_to_reg(index));
+
+        return 0;
+}
+
+static u8 plt_clk_get_parent(struct clk_hw *hw)
+{
+        struct clk_plt *clk = to_clk_plt(hw);
+        u32 value;
+
+        value = readl(clk->reg);
+
+        return plt_reg_to_parent(value);
+}
+
+static int plt_clk_enable(struct clk_hw *hw)
+{
+        struct clk_plt *clk = to_clk_plt(hw);
+
+        plt_clk_reg_update(clk, PMC_MASK_CLK_CTL, PMC_CLK_CTL_FORCE_ON);
+
+        return 0;
+}
+
+static void plt_clk_disable(struct clk_hw *hw)
+{
+        struct clk_plt *clk = to_clk_plt(hw);
+
+        plt_clk_reg_update(clk, PMC_MASK_CLK_CTL, PMC_CLK_CTL_FORCE_OFF);
+}
+
+static int plt_clk_is_enabled(struct clk_hw *hw)
+{
+        struct clk_plt *clk = to_clk_plt(hw);
+        u32 value;
+
+        value = readl(clk->reg);
+
+        return plt_reg_to_enabled(value);
+}
+
+static const struct clk_ops plt_clk_ops = {
+        .enable = plt_clk_enable,
+        .disable = plt_clk_disable,
+        .is_enabled = plt_clk_is_enabled,
+        .get_parent = plt_clk_get_parent,
+        .set_parent = plt_clk_set_parent,
+        .determine_rate = __clk_mux_determine_rate,
+};
+
+static struct clk_plt *plt_clk_register(struct platform_device *pdev, int id,
+                                        void __iomem *base,
+                                        const char **parent_names,
+                                        int num_parents)
+{
+        struct clk_plt *pclk;
+        struct clk_init_data init;
+        int ret;
+
+        pclk = devm_kzalloc(&pdev->dev, sizeof(*pclk), GFP_KERNEL);
+        if (!pclk)
+                return ERR_PTR(-ENOMEM);
+
+        init.name =  kasprintf(GFP_KERNEL, "%s_%d", PLT_CLK_NAME_BASE, id);
+        init.ops = &plt_clk_ops;
+        init.flags = 0;
+        init.parent_names = parent_names;
+        init.num_parents = num_parents;
+
+        pclk->hw.init = &init;
+        pclk->reg = base + PMC_CLK_CTL_OFFSET + id * PMC_CLK_CTL_SIZE;
+        spin_lock_init(&pclk->lock);
+
+        ret = devm_clk_hw_register(&pdev->dev, &pclk->hw);
+        if (ret) {
+                pclk = ERR_PTR(ret);
+                goto err_free_init;
+        }
+
+        pclk->lookup = clkdev_hw_create(&pclk->hw, init.name, NULL);
+        if (!pclk->lookup) {
+                pclk = ERR_PTR(-ENOMEM);
+                goto err_free_init;
+        }
+
+err_free_init:
+        kfree(init.name);
+        return pclk;
+}
+
+static void plt_clk_unregister(struct clk_plt *pclk)
+{
+        clkdev_drop(pclk->lookup);
+}
+
+static struct clk_plt_fixed *plt_clk_register_fixed_rate(struct platform_device *pdev,
+                                                 const char *name,
+                                                 const char *parent_name,
+                                                 unsigned long fixed_rate)
+{
+        struct clk_plt_fixed *pclk;
+
+        pclk = devm_kzalloc(&pdev->dev, sizeof(*pclk), GFP_KERNEL);
+        if (!pclk)
+                return ERR_PTR(-ENOMEM);
+
+        pclk->clk = clk_hw_register_fixed_rate(&pdev->dev, name, parent_name,
+                                               0, fixed_rate);
+        if (IS_ERR(pclk->clk))
+                return ERR_CAST(pclk->clk);
+
+        pclk->lookup = clkdev_hw_create(pclk->clk, name, NULL);
+        if (!pclk->lookup) {
+                clk_hw_unregister_fixed_rate(pclk->clk);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        return pclk;
+}
+
+static void plt_clk_unregister_fixed_rate(struct clk_plt_fixed *pclk)
+{
+        clkdev_drop(pclk->lookup);
+        clk_hw_unregister_fixed_rate(pclk->clk);
+}
+
+static void plt_clk_unregister_fixed_rate_loop(struct clk_plt_data *data,
+                                               unsigned int i)
+{
+        while (i--)
+                plt_clk_unregister_fixed_rate(data->parents[i]);
+}
+
+static void plt_clk_free_parent_names_loop(const char **parent_names,
+                                           unsigned int i)
+{
+        while (i--)
+                kfree_const(parent_names[i]);
+        kfree(parent_names);
+}
+
+static void plt_clk_unregister_loop(struct clk_plt_data *data,
+                                    unsigned int i)
+{
+        while (i--)
+                plt_clk_unregister(data->clks[i]);
+}
+
+static const char **plt_clk_register_parents(struct platform_device *pdev,
+                                             struct clk_plt_data *data,
+                                             const struct pmc_clk *clks)
+{
+        const char **parent_names;
+        unsigned int i;
+        int err;
+        int nparents = 0;
+
+        data->nparents = 0;
+        while (clks[nparents].name)
+                nparents++;
+
+        data->parents = devm_kcalloc(&pdev->dev, nparents,
+                                     sizeof(*data->parents), GFP_KERNEL);
+        if (!data->parents)
+                return ERR_PTR(-ENOMEM);
+
+        parent_names = kcalloc(nparents, sizeof(*parent_names),
+                               GFP_KERNEL);
+        if (!parent_names)
+                return ERR_PTR(-ENOMEM);
+
+        for (i = 0; i < nparents; i++) {
+                data->parents[i] =
+                        plt_clk_register_fixed_rate(pdev, clks[i].name,
+                                                    clks[i].parent_name,
+                                                    clks[i].freq);
+                if (IS_ERR(data->parents[i])) {
+                        err = PTR_ERR(data->parents[i]);
+                        goto err_unreg;
+                }
+                parent_names[i] = kstrdup_const(clks[i].name, GFP_KERNEL);
+        }
+
+        data->nparents = nparents;
+        return parent_names;
+
+err_unreg:
+        plt_clk_unregister_fixed_rate_loop(data, i);
+        plt_clk_free_parent_names_loop(parent_names, i);
+        return ERR_PTR(err);
+}
+
+static void plt_clk_unregister_parents(struct clk_plt_data *data)
+{
+        plt_clk_unregister_fixed_rate_loop(data, data->nparents);
+}
+
+static int plt_clk_probe(struct platform_device *pdev)
+{
+        const struct pmc_clk_data *pmc_data;
+        const char **parent_names;
+        struct clk_plt_data *data;
+        unsigned int i;
+        int err;
+
+        pmc_data = dev_get_platdata(&pdev->dev);
+        if (!pmc_data || !pmc_data->clks)
+                return -EINVAL;
+
+        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
+
+        parent_names = plt_clk_register_parents(pdev, data, pmc_data->clks);
+        if (IS_ERR(parent_names))
+                return PTR_ERR(parent_names);
+
+        for (i = 0; i < PMC_CLK_NUM; i++) {
+                data->clks[i] = plt_clk_register(pdev, i, pmc_data->base,
+                                                 parent_names, data->nparents);
+                if (IS_ERR(data->clks[i])) {
+                        err = PTR_ERR(data->clks[i]);
+                        goto err_unreg_clk_plt;
+                }
+        }
+
+        plt_clk_free_parent_names_loop(parent_names, data->nparents);
+
+        platform_set_drvdata(pdev, data);
+        return 0;
+
+err_unreg_clk_plt:
+        plt_clk_unregister_loop(data, i);
+        plt_clk_unregister_parents(data);
+        plt_clk_free_parent_names_loop(parent_names, data->nparents);
+        return err;
+}
+
+static int plt_clk_remove(struct platform_device *pdev)
+{
+        struct clk_plt_data *data;
+
+        data = platform_get_drvdata(pdev);
+
+        plt_clk_unregister_loop(data, PMC_CLK_NUM);
+        plt_clk_unregister_parents(data);
+        return 0;
+}
+
+static struct platform_driver plt_clk_driver = {
+        .driver = {
+                .name = "clk-pmc-atom",
+        },
+        .probe = plt_clk_probe,
+        .remove = plt_clk_remove,
+};
+builtin_platform_driver(plt_clk_driver);