clk: Add APM X-Gene SoC clock driver

clk: Add APM X-Gene SoC clock driver for reference, PLL, and device clocks.

Signed-off-by: Loc Ho <lho@apm.com>
Signed-off-by: Kumar Sankaran <ksankaran@apm.com>
Signed-off-by: Vinayak Kale <vkale@apm.com>
Signed-off-by: Feng Kan <fkan@apm.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

3 files changed, 529 insertions, 0 deletions

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 279407a36391..dd37f91289d2 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -93,6 +93,13 @@ config CLK_PPC_CORENET
           This adds the clock driver support for Freescale PowerPC corenet
           platforms using common clock framework.
 
+config COMMON_CLK_XGENE
+        bool "Clock driver for APM XGene SoC"
+        default y
+        depends on ARM64
+        ---help---
+          Sypport for the APM X-Gene SoC reference, PLL, and device clocks.
+
 endmenu
 
 source "drivers/clk/mvebu/Kconfig"
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 7b111062ccba..270f3fd2fbc0 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_ARCH_VT8500)	+= clk-vt8500.o
 obj-$(CONFIG_ARCH_ZYNQ)         += zynq/
 obj-$(CONFIG_ARCH_TEGRA)        += tegra/
 obj-$(CONFIG_PLAT_SAMSUNG)      += samsung/
+obj-$(CONFIG_COMMON_CLK_XGENE)  += clk-xgene.o
 
 obj-$(CONFIG_X86)               += x86/
 
diff --git a/drivers/clk/clk-xgene.c b/drivers/clk/clk-xgene.c
new file mode 100644
index 000000000000..dd8a62d8f11f
--- /dev/null
+++ b/drivers/clk/clk-xgene.c
@@ -0,0 +1,521 @@
+/*
+ * clk-xgene.c - AppliedMicro X-Gene Clock Interface
+ *
+ * Copyright (c) 2013, Applied Micro Circuits Corporation
+ * Author: Loc Ho <lho@apm.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/module.h>
+#include <linux/spinlock.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/of_address.h>
+#include <asm/setup.h>
+
+/* Register SCU_PCPPLL bit fields */
+#define N_DIV_RD(src)                   (((src) & 0x000001ff))
+
+/* Register SCU_SOCPLL bit fields */
+#define CLKR_RD(src)                    (((src) & 0x07000000)>>24)
+#define CLKOD_RD(src)                   (((src) & 0x00300000)>>20)
+#define REGSPEC_RESET_F1_MASK           0x00010000
+#define CLKF_RD(src)                    (((src) & 0x000001ff))
+
+#define XGENE_CLK_DRIVER_VER            "0.1"
+
+static DEFINE_SPINLOCK(clk_lock);
+
+static inline u32 xgene_clk_read(void *csr)
+{
+        return readl_relaxed(csr);
+}
+
+static inline void xgene_clk_write(u32 data, void *csr)
+{
+        return writel_relaxed(data, csr);
+}
+
+/* PLL Clock */
+enum xgene_pll_type {
+        PLL_TYPE_PCP = 0,
+        PLL_TYPE_SOC = 1,
+};
+
+struct xgene_clk_pll {
+        struct clk_hw   hw;
+        const char      *name;
+        void __iomem    *reg;
+        spinlock_t      *lock;
+        u32             pll_offset;
+        enum xgene_pll_type     type;
+};
+
+#define to_xgene_clk_pll(_hw) container_of(_hw, struct xgene_clk_pll, hw)
+
+static int xgene_clk_pll_is_enabled(struct clk_hw *hw)
+{
+        struct xgene_clk_pll *pllclk = to_xgene_clk_pll(hw);
+        u32 data;
+
+        data = xgene_clk_read(pllclk->reg + pllclk->pll_offset);
+        pr_debug("%s pll %s\n", pllclk->name,
+                data & REGSPEC_RESET_F1_MASK ? "disabled" : "enabled");
+
+        return data & REGSPEC_RESET_F1_MASK ? 0 : 1;
+}
+
+static unsigned long xgene_clk_pll_recalc_rate(struct clk_hw *hw,
+                                unsigned long parent_rate)
+{
+        struct xgene_clk_pll *pllclk = to_xgene_clk_pll(hw);
+        unsigned long fref;
+        unsigned long fvco;
+        u32 pll;
+        u32 nref;
+        u32 nout;
+        u32 nfb;
+
+        pll = xgene_clk_read(pllclk->reg + pllclk->pll_offset);
+
+        if (pllclk->type == PLL_TYPE_PCP) {
+                /*
+                 * PLL VCO = Reference clock * NF
+                 * PCP PLL = PLL_VCO / 2
+                 */
+                nout = 2;
+                fvco = parent_rate * (N_DIV_RD(pll) + 4);
+        } else {
+                /*
+                 * Fref = Reference Clock / NREF;
+                 * Fvco = Fref * NFB;
+                 * Fout = Fvco / NOUT;
+                 */
+                nref = CLKR_RD(pll) + 1;
+                nout = CLKOD_RD(pll) + 1;
+                nfb = CLKF_RD(pll);
+                fref = parent_rate / nref;
+                fvco = fref * nfb;
+        }
+        pr_debug("%s pll recalc rate %ld parent %ld\n", pllclk->name,
+                fvco / nout, parent_rate);
+
+        return fvco / nout;
+}
+
+const struct clk_ops xgene_clk_pll_ops = {
+        .is_enabled = xgene_clk_pll_is_enabled,
+        .recalc_rate = xgene_clk_pll_recalc_rate,
+};
+
+static struct clk *xgene_register_clk_pll(struct device *dev,
+        const char *name, const char *parent_name,
+        unsigned long flags, void __iomem *reg, u32 pll_offset,
+        u32 type, spinlock_t *lock)
+{
+        struct xgene_clk_pll *apmclk;
+        struct clk *clk;
+        struct clk_init_data init;
+
+        /* allocate the APM clock structure */
+        apmclk = kzalloc(sizeof(*apmclk), GFP_KERNEL);
+        if (!apmclk) {
+                pr_err("%s: could not allocate APM clk\n", __func__);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        init.name = name;
+        init.ops = &xgene_clk_pll_ops;
+        init.flags = flags;
+        init.parent_names = parent_name ? &parent_name : NULL;
+        init.num_parents = parent_name ? 1 : 0;
+
+        apmclk->name = name;
+        apmclk->reg = reg;
+        apmclk->lock = lock;
+        apmclk->pll_offset = pll_offset;
+        apmclk->type = type;
+        apmclk->hw.init = &init;
+
+        /* Register the clock */
+        clk = clk_register(dev, &apmclk->hw);
+        if (IS_ERR(clk)) {
+                pr_err("%s: could not register clk %s\n", __func__, name);
+                kfree(apmclk);
+                return NULL;
+        }
+        return clk;
+}
+
+static void xgene_pllclk_init(struct device_node *np, enum xgene_pll_type pll_type)
+{
+        const char *clk_name = np->full_name;
+        struct clk *clk;
+        void *reg;
+
+        reg = of_iomap(np, 0);
+        if (reg == NULL) {
+                pr_err("Unable to map CSR register for %s\n", np->full_name);
+                return;
+        }
+        of_property_read_string(np, "clock-output-names", &clk_name);
+        clk = xgene_register_clk_pll(NULL,
+                        clk_name, of_clk_get_parent_name(np, 0),
+                        CLK_IS_ROOT, reg, 0, pll_type, &clk_lock);
+        if (!IS_ERR(clk)) {
+                of_clk_add_provider(np, of_clk_src_simple_get, clk);
+                clk_register_clkdev(clk, clk_name, NULL);
+                pr_debug("Add %s clock PLL\n", clk_name);
+        }
+}
+
+static void xgene_socpllclk_init(struct device_node *np)
+{
+        xgene_pllclk_init(np, PLL_TYPE_SOC);
+}
+
+static void xgene_pcppllclk_init(struct device_node *np)
+{
+        xgene_pllclk_init(np, PLL_TYPE_PCP);
+}
+
+/* IP Clock */
+struct xgene_dev_parameters {
+        void __iomem *csr_reg;          /* CSR for IP clock */
+        u32 reg_clk_offset;             /* Offset to clock enable CSR */
+        u32 reg_clk_mask;               /* Mask bit for clock enable */
+        u32 reg_csr_offset;             /* Offset to CSR reset */
+        u32 reg_csr_mask;               /* Mask bit for disable CSR reset */
+        void __iomem *divider_reg;      /* CSR for divider */
+        u32 reg_divider_offset;         /* Offset to divider register */
+        u32 reg_divider_shift;          /* Bit shift to divider field */
+        u32 reg_divider_width;          /* Width of the bit to divider field */
+};
+
+struct xgene_clk {
+        struct clk_hw   hw;
+        const char      *name;
+        spinlock_t      *lock;
+        struct xgene_dev_parameters     param;
+};
+
+#define to_xgene_clk(_hw) container_of(_hw, struct xgene_clk, hw)
+
+static int xgene_clk_enable(struct clk_hw *hw)
+{
+        struct xgene_clk *pclk = to_xgene_clk(hw);
+        unsigned long flags = 0;
+        u32 data;
+
+        if (pclk->lock)
+                spin_lock_irqsave(pclk->lock, flags);
+
+        if (pclk->param.csr_reg != NULL) {
+                pr_debug("%s clock enabled\n", pclk->name);
+                /* First enable the clock */
+                data = xgene_clk_read(pclk->param.csr_reg +
+                                        pclk->param.reg_clk_offset);
+                data |= pclk->param.reg_clk_mask;
+                xgene_clk_write(data, pclk->param.csr_reg +
+                                        pclk->param.reg_clk_offset);
+                pr_debug("%s clock PADDR base 0x%016LX clk offset 0x%08X mask 0x%08X value 0x%08X\n",
+                        pclk->name, __pa(pclk->param.csr_reg),
+                        pclk->param.reg_clk_offset, pclk->param.reg_clk_mask,
+                        data);
+
+                /* Second enable the CSR */
+                data = xgene_clk_read(pclk->param.csr_reg +
+                                        pclk->param.reg_csr_offset);
+                data &= ~pclk->param.reg_csr_mask;
+                xgene_clk_write(data, pclk->param.csr_reg +
+                                        pclk->param.reg_csr_offset);
+                pr_debug("%s CSR RESET PADDR base 0x%016LX csr offset 0x%08X mask 0x%08X value 0x%08X\n",
+                        pclk->name, __pa(pclk->param.csr_reg),
+                        pclk->param.reg_csr_offset, pclk->param.reg_csr_mask,
+                        data);
+        }
+
+        if (pclk->lock)
+                spin_unlock_irqrestore(pclk->lock, flags);
+
+        return 0;
+}
+
+static void xgene_clk_disable(struct clk_hw *hw)
+{
+        struct xgene_clk *pclk = to_xgene_clk(hw);
+        unsigned long flags = 0;
+        u32 data;
+
+        if (pclk->lock)
+                spin_lock_irqsave(pclk->lock, flags);
+
+        if (pclk->param.csr_reg != NULL) {
+                pr_debug("%s clock disabled\n", pclk->name);
+                /* First put the CSR in reset */
+                data = xgene_clk_read(pclk->param.csr_reg +
+                                        pclk->param.reg_csr_offset);
+                data |= pclk->param.reg_csr_mask;
+                xgene_clk_write(data, pclk->param.csr_reg +
+                                        pclk->param.reg_csr_offset);
+
+                /* Second disable the clock */
+                data = xgene_clk_read(pclk->param.csr_reg +
+                                        pclk->param.reg_clk_offset);
+                data &= ~pclk->param.reg_clk_mask;
+                xgene_clk_write(data, pclk->param.csr_reg +
+                                        pclk->param.reg_clk_offset);
+        }
+
+        if (pclk->lock)
+                spin_unlock_irqrestore(pclk->lock, flags);
+}
+
+static int xgene_clk_is_enabled(struct clk_hw *hw)
+{
+        struct xgene_clk *pclk = to_xgene_clk(hw);
+        u32 data = 0;
+
+        if (pclk->param.csr_reg != NULL) {
+                pr_debug("%s clock checking\n", pclk->name);
+                data = xgene_clk_read(pclk->param.csr_reg +
+                                        pclk->param.reg_clk_offset);
+                pr_debug("%s clock is %s\n", pclk->name,
+                        data & pclk->param.reg_clk_mask ? "enabled" :
+                                                        "disabled");
+        }
+
+        if (pclk->param.csr_reg == NULL)
+                return 1;
+        return data & pclk->param.reg_clk_mask ? 1 : 0;
+}
+
+static unsigned long xgene_clk_recalc_rate(struct clk_hw *hw,
+                                unsigned long parent_rate)
+{
+        struct xgene_clk *pclk = to_xgene_clk(hw);
+        u32 data;
+
+        if (pclk->param.divider_reg) {
+                data = xgene_clk_read(pclk->param.divider_reg +
+                                        pclk->param.reg_divider_offset);
+                data >>= pclk->param.reg_divider_shift;
+                data &= (1 << pclk->param.reg_divider_width) - 1;
+
+                pr_debug("%s clock recalc rate %ld parent %ld\n",
+                        pclk->name, parent_rate / data, parent_rate);
+                return parent_rate / data;
+        } else {
+                pr_debug("%s clock recalc rate %ld parent %ld\n",
+                        pclk->name, parent_rate, parent_rate);
+                return parent_rate;
+        }
+}
+
+static int xgene_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+                                unsigned long parent_rate)
+{
+        struct xgene_clk *pclk = to_xgene_clk(hw);
+        unsigned long flags = 0;
+        u32 data;
+        u32 divider;
+        u32 divider_save;
+
+        if (pclk->lock)
+                spin_lock_irqsave(pclk->lock, flags);
+
+        if (pclk->param.divider_reg) {
+                /* Let's compute the divider */
+                if (rate > parent_rate)
+                        rate = parent_rate;
+                divider_save = divider = parent_rate / rate; /* Rounded down */
+                divider &= (1 << pclk->param.reg_divider_width) - 1;
+                divider <<= pclk->param.reg_divider_shift;
+
+                /* Set new divider */
+                data = xgene_clk_read(pclk->param.divider_reg +
+                                pclk->param.reg_divider_offset);
+                data &= ~((1 << pclk->param.reg_divider_width) - 1);
+                data |= divider;
+                xgene_clk_write(data, pclk->param.divider_reg +
+                                        pclk->param.reg_divider_offset);
+                pr_debug("%s clock set rate %ld\n", pclk->name,
+                        parent_rate / divider_save);
+        } else {
+                divider_save = 1;
+        }
+
+        if (pclk->lock)
+                spin_unlock_irqrestore(pclk->lock, flags);
+
+        return parent_rate / divider_save;
+}
+
+static long xgene_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+                                unsigned long *prate)
+{
+        struct xgene_clk *pclk = to_xgene_clk(hw);
+        unsigned long parent_rate = *prate;
+        u32 divider;
+
+        if (pclk->param.divider_reg) {
+                /* Let's compute the divider */
+                if (rate > parent_rate)
+                        rate = parent_rate;
+                divider = parent_rate / rate;   /* Rounded down */
+        } else {
+                divider = 1;
+        }
+
+        return parent_rate / divider;
+}
+
+const struct clk_ops xgene_clk_ops = {
+        .enable = xgene_clk_enable,
+        .disable = xgene_clk_disable,
+        .is_enabled = xgene_clk_is_enabled,
+        .recalc_rate = xgene_clk_recalc_rate,
+        .set_rate = xgene_clk_set_rate,
+        .round_rate = xgene_clk_round_rate,
+};
+
+static struct clk *xgene_register_clk(struct device *dev,
+                const char *name, const char *parent_name,
+                struct xgene_dev_parameters *parameters, spinlock_t *lock)
+{
+        struct xgene_clk *apmclk;
+        struct clk *clk;
+        struct clk_init_data init;
+        int rc;
+
+        /* allocate the APM clock structure */
+        apmclk = kzalloc(sizeof(*apmclk), GFP_KERNEL);
+        if (!apmclk) {
+                pr_err("%s: could not allocate APM clk\n", __func__);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        init.name = name;
+        init.ops = &xgene_clk_ops;
+        init.flags = 0;
+        init.parent_names = parent_name ? &parent_name : NULL;
+        init.num_parents = parent_name ? 1 : 0;
+
+        apmclk->name = name;
+        apmclk->lock = lock;
+        apmclk->hw.init = &init;
+        apmclk->param = *parameters;
+
+        /* Register the clock */
+        clk = clk_register(dev, &apmclk->hw);
+        if (IS_ERR(clk)) {
+                pr_err("%s: could not register clk %s\n", __func__, name);
+                kfree(apmclk);
+                return clk;
+        }
+
+        /* Register the clock for lookup */
+        rc = clk_register_clkdev(clk, name, NULL);
+        if (rc != 0) {
+                pr_err("%s: could not register lookup clk %s\n",
+                        __func__, name);
+        }
+        return clk;
+}
+
+static void __init xgene_devclk_init(struct device_node *np)
+{
+        const char *clk_name = np->full_name;
+        struct clk *clk;
+        struct resource res;
+        int rc;
+        struct xgene_dev_parameters parameters;
+        int i;
+
+        /* Check if the entry is disabled */
+        if (!of_device_is_available(np))
+                return;
+
+        /* Parse the DTS register for resource */
+        parameters.csr_reg = NULL;
+        parameters.divider_reg = NULL;
+        for (i = 0; i < 2; i++) {
+                void *map_res;
+                rc = of_address_to_resource(np, i, &res);
+                if (rc != 0) {
+                        if (i == 0) {
+                                pr_err("no DTS register for %s\n", 
+                                        np->full_name);
+                                return;
+                        }
+                        break;
+                }
+                map_res = of_iomap(np, i);
+                if (map_res == NULL) {
+                        pr_err("Unable to map resource %d for %s\n",
+                                i, np->full_name);
+                        goto err;
+                }
+                if (strcmp(res.name, "div-reg") == 0)
+                        parameters.divider_reg = map_res;
+                else /* if (strcmp(res->name, "csr-reg") == 0) */
+                        parameters.csr_reg = map_res;
+        }
+        if (of_property_read_u32(np, "csr-offset", &parameters.reg_csr_offset))
+                parameters.reg_csr_offset = 0;
+        if (of_property_read_u32(np, "csr-mask", &parameters.reg_csr_mask))
+                parameters.reg_csr_mask = 0xF;
+        if (of_property_read_u32(np, "enable-offset",
+                                &parameters.reg_clk_offset))
+                parameters.reg_clk_offset = 0x8;
+        if (of_property_read_u32(np, "enable-mask", &parameters.reg_clk_mask))
+                parameters.reg_clk_mask = 0xF;
+        if (of_property_read_u32(np, "divider-offset",
+                                &parameters.reg_divider_offset))
+                parameters.reg_divider_offset = 0;
+        if (of_property_read_u32(np, "divider-width",
+                                &parameters.reg_divider_width))
+                parameters.reg_divider_width = 0;
+        if (of_property_read_u32(np, "divider-shift",
+                                &parameters.reg_divider_shift))
+                parameters.reg_divider_shift = 0;
+        of_property_read_string(np, "clock-output-names", &clk_name);
+
+        clk = xgene_register_clk(NULL, clk_name,
+                of_clk_get_parent_name(np, 0), &parameters, &clk_lock);
+        if (IS_ERR(clk))
+                goto err;
+        pr_debug("Add %s clock\n", clk_name);
+        rc = of_clk_add_provider(np, of_clk_src_simple_get, clk);
+        if (rc != 0)
+                pr_err("%s: could register provider clk %s\n", __func__,
+                        np->full_name);
+
+        return;
+
+err:
+        if (parameters.csr_reg)
+                iounmap(parameters.csr_reg);
+        if (parameters.divider_reg)
+                iounmap(parameters.divider_reg);
+}
+
+CLK_OF_DECLARE(xgene_socpll_clock, "apm,xgene-socpll-clock", xgene_socpllclk_init);
+CLK_OF_DECLARE(xgene_pcppll_clock, "apm,xgene-pcppll-clock", xgene_pcppllclk_init);
+CLK_OF_DECLARE(xgene_dev_clock, "apm,xgene-device-clock", xgene_devclk_init);