ARM: S3C2440: CPUFREQ: Add core support.

Add core support for frequency scaling on the S3C2440 SoC.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

3 files changed, 318 insertions, 0 deletions

diff --git a/arch/arm/plat-s3c24xx/Kconfig b/arch/arm/plat-s3c24xx/Kconfig
index a547c79ed6c..feb9db8886b 100644
--- a/arch/arm/plat-s3c24xx/Kconfig
+++ b/arch/arm/plat-s3c24xx/Kconfig
@@ -34,6 +34,14 @@ config CPU_S3C244X
         help
           Support for S3C2440 and S3C2442 Samsung Mobile CPU based systems.
 
+config S3C2440_CPUFREQ
+        bool "S3C2440/S3C2442 CPU Frequency scaling support"
+        depends on CPU_FREQ_S3C24XX && (CPU_S3C2440 || CPU_S3C2442)
+        select S3C2410_CPUFREQ_UTILS
+        default y
+        help
+          CPU Frequency scaling support for S3C2440 and S3C2442 SoC CPUs.
+
 config S3C24XX_PWM
         bool "PWM device support"
         select HAVE_PWM
diff --git a/arch/arm/plat-s3c24xx/Makefile b/arch/arm/plat-s3c24xx/Makefile
index b28fe9cb0e5..b73f2e17b16 100644
--- a/arch/arm/plat-s3c24xx/Makefile
+++ b/arch/arm/plat-s3c24xx/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_CPU_FREQ_S3C24XX)	+= cpu-freq.o
 obj-$(CONFIG_CPU_S3C244X)       += s3c244x.o
 obj-$(CONFIG_CPU_S3C244X)       += s3c244x-irq.o
 obj-$(CONFIG_CPU_S3C244X)       += s3c244x-clock.o
+obj-$(CONFIG_S3C2440_CPUFREQ)   += s3c2440-cpufreq.o
 obj-$(CONFIG_PM_SIMTEC)         += pm-simtec.o
 obj-$(CONFIG_PM)                += pm.o
 obj-$(CONFIG_PM)                += irq-pm.o
diff --git a/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c b/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c
new file mode 100644
index 00000000000..c177a20319e
--- /dev/null
+++ b/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c
@@ -0,0 +1,309 @@
+/* linux/arch/arm/plat-s3c24xx/s3c2440-cpufreq.c
+ *
+ * Copyright (c) 2006,2008,2009 Simtec Electronics
+ *      http://armlinux.simtec.co.uk/
+ *      Ben Dooks <ben@simtec.co.uk>
+ *      Vincent Sanders <vince@simtec.co.uk>
+ *
+ * S3C2440/S3C2442 CPU Frequency scaling
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/cpufreq.h>
+#include <linux/sysdev.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+
+#include <mach/hardware.h>
+
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+#include <mach/regs-clock.h>
+
+#include <plat/cpu.h>
+#include <plat/cpu-freq-core.h>
+#include <plat/clock.h>
+
+static struct clk *xtal;
+static struct clk *fclk;
+static struct clk *hclk;
+static struct clk *armclk;
+
+/* HDIV: 1, 2, 3, 4, 6, 8 */
+
+static inline int within_khz(unsigned long a, unsigned long b)
+{
+        long diff = a - b;
+
+        return (diff >= -1000 && diff <= 1000);
+}
+
+/**
+ * s3c2440_cpufreq_calcdivs - calculate divider settings
+ * @cfg: The cpu frequency settings.
+ *
+ * Calcualte the divider values for the given frequency settings
+ * specified in @cfg. The values are stored in @cfg for later use
+ * by the relevant set routine if the request settings can be reached.
+ */
+int s3c2440_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
+{
+        unsigned int hdiv, pdiv;
+        unsigned long hclk, fclk, armclk;
+        unsigned long hclk_max;
+
+        fclk = cfg->freq.fclk;
+        armclk = cfg->freq.armclk;
+        hclk_max = cfg->max.hclk;
+
+        s3c_freq_dbg("%s: fclk is %lu, armclk %lu, max hclk %lu\n",
+                     __func__, fclk, armclk, hclk_max);
+
+        if (armclk > fclk) {
+                printk(KERN_WARNING "%s: armclk > fclk\n", __func__);
+                armclk = fclk;
+        }
+
+        /* if we are in DVS, we need HCLK to be <= ARMCLK */
+        if (armclk < fclk && armclk < hclk_max)
+                hclk_max = armclk;
+
+        for (hdiv = 1; hdiv < 9; hdiv++) {
+                if (hdiv == 5 || hdiv == 7)
+                        hdiv++;
+
+                hclk = (fclk / hdiv);
+                if (hclk <= hclk_max || within_khz(hclk, hclk_max))
+                        break;
+        }
+
+        s3c_freq_dbg("%s: hclk %lu, div %d\n", __func__, hclk, hdiv);
+
+        if (hdiv > 8)
+                goto invalid;
+
+        pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
+
+        if ((hclk / pdiv) > cfg->max.pclk)
+                pdiv++;
+
+        s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);
+
+        if (pdiv > 2)
+                goto invalid;
+
+        pdiv *= hdiv;
+
+        /* calculate a valid armclk */
+
+        if (armclk < hclk)
+                armclk = hclk;
+
+        /* if we're running armclk lower than fclk, this really means
+         * that the system should go into dvs mode, which means that
+         * armclk is connected to hclk. */
+        if (armclk < fclk) {
+                cfg->divs.dvs = 1;
+                armclk = hclk;
+        } else
+                cfg->divs.dvs = 0;
+
+        cfg->freq.armclk = armclk;
+
+        /* store the result, and then return */
+
+        cfg->divs.h_divisor = hdiv;
+        cfg->divs.p_divisor = pdiv;
+
+        return 0;
+
+ invalid:
+        return -EINVAL;
+}
+
+#define CAMDIVN_HCLK_HALF (S3C2440_CAMDIVN_HCLK3_HALF | \
+                           S3C2440_CAMDIVN_HCLK4_HALF)
+
+/**
+ * s3c2440_cpufreq_setdivs - set the cpu frequency divider settings
+ * @cfg: The cpu frequency settings.
+ *
+ * Set the divisors from the settings in @cfg, which where generated
+ * during the calculation phase by s3c2440_cpufreq_calcdivs().
+ */
+static void s3c2440_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
+{
+        unsigned long clkdiv, camdiv;
+
+        s3c_freq_dbg("%s: divsiors: h=%d, p=%d\n", __func__,
+                     cfg->divs.h_divisor, cfg->divs.p_divisor);
+
+        clkdiv = __raw_readl(S3C2410_CLKDIVN);
+        camdiv = __raw_readl(S3C2440_CAMDIVN);
+
+        clkdiv &= ~(S3C2440_CLKDIVN_HDIVN_MASK | S3C2440_CLKDIVN_PDIVN);
+        camdiv &= ~CAMDIVN_HCLK_HALF;
+
+        switch (cfg->divs.h_divisor) {
+        case 1:
+                clkdiv |= S3C2440_CLKDIVN_HDIVN_1;
+                break;
+
+        case 2:
+                clkdiv |= S3C2440_CLKDIVN_HDIVN_2;
+                break;
+
+        case 6:
+                camdiv |= S3C2440_CAMDIVN_HCLK3_HALF;
+        case 3:
+                clkdiv |= S3C2440_CLKDIVN_HDIVN_3_6;
+                break;
+
+        case 8:
+                camdiv |= S3C2440_CAMDIVN_HCLK4_HALF;
+        case 4:
+                clkdiv |= S3C2440_CLKDIVN_HDIVN_4_8;
+                break;
+
+        default:
+                BUG();  /* we don't expect to get here. */
+        }
+
+        if (cfg->divs.p_divisor != cfg->divs.h_divisor)
+                clkdiv |= S3C2440_CLKDIVN_PDIVN;
+
+        /* todo - set pclk. */
+
+        /* Write the divisors first with hclk intentionally halved so that
+         * when we write clkdiv we will under-frequency instead of over. We
+         * then make a short delay and remove the hclk halving if necessary.
+         */
+
+        __raw_writel(camdiv | CAMDIVN_HCLK_HALF, S3C2440_CAMDIVN);
+        __raw_writel(clkdiv, S3C2410_CLKDIVN);
+
+        ndelay(20);
+        __raw_writel(camdiv, S3C2440_CAMDIVN);
+
+        clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);
+}
+
+static int run_freq_for(unsigned long max_hclk, unsigned long fclk,
+                        int *divs,
+                        struct cpufreq_frequency_table *table,
+                        size_t table_size)
+{
+        unsigned long freq;
+        int index = 0;
+        int div;
+
+        for (div = *divs; div > 0; div = *divs++) {
+                freq = fclk / div;
+
+                if (freq > max_hclk && div != 1)
+                        continue;
+
+                freq /= 1000; /* table is in kHz */
+                index = s3c_cpufreq_addfreq(table, index, table_size, freq);
+                if (index < 0)
+                        break;
+        }
+
+        return index;
+}
+
+static int hclk_divs[] = { 1, 2, 3, 4, 6, 8, -1 };
+
+static int s3c2440_cpufreq_calctable(struct s3c_cpufreq_config *cfg,
+                                     struct cpufreq_frequency_table *table,
+                                     size_t table_size)
+{
+        int ret;
+
+        WARN_ON(cfg->info == NULL);
+        WARN_ON(cfg->board == NULL);
+
+        ret = run_freq_for(cfg->info->max.hclk,
+                           cfg->info->max.fclk,
+                           hclk_divs,
+                           table, table_size);
+
+        s3c_freq_dbg("%s: returning %d\n", __func__, ret);
+
+        return ret;
+}
+
+struct s3c_cpufreq_info s3c2440_cpufreq_info = {
+        .max            = {
+                .fclk   = 400000000,
+                .hclk   = 133333333,
+                .pclk   =  66666666,
+        },
+
+        .locktime_m     = 300,
+        .locktime_u     = 300,
+        .locktime_bits  = 16,
+
+        .name           = "s3c244x",
+        .calc_iotiming  = s3c2410_iotiming_calc,
+        .set_iotiming   = s3c2410_iotiming_set,
+        .get_iotiming   = s3c2410_iotiming_get,
+        .set_fvco       = s3c2410_set_fvco,
+
+        .set_refresh    = s3c2410_cpufreq_setrefresh,
+        .set_divs       = s3c2440_cpufreq_setdivs,
+        .calc_divs      = s3c2440_cpufreq_calcdivs,
+        .calc_freqtable = s3c2440_cpufreq_calctable,
+
+        .resume_clocks  = s3c244x_setup_clocks,
+};
+
+static int s3c2440_cpufreq_add(struct sys_device *sysdev)
+{
+        xtal = s3c_cpufreq_clk_get(NULL, "xtal");
+        hclk = s3c_cpufreq_clk_get(NULL, "hclk");
+        fclk = s3c_cpufreq_clk_get(NULL, "fclk");
+        armclk = s3c_cpufreq_clk_get(NULL, "armclk");
+
+        if (IS_ERR(xtal) || IS_ERR(hclk) || IS_ERR(fclk) || IS_ERR(armclk)) {
+                printk(KERN_ERR "%s: failed to get clocks\n", __func__);
+                return -ENOENT;
+        }
+
+        return s3c_cpufreq_register(&s3c2440_cpufreq_info);
+}
+
+static struct sysdev_driver s3c2440_cpufreq_driver = {
+        .add            = s3c2440_cpufreq_add,
+};
+
+static int s3c2440_cpufreq_init(void)
+{
+        return sysdev_driver_register(&s3c2440_sysclass,
+                                      &s3c2440_cpufreq_driver);
+}
+
+/* arch_initcall adds the clocks we need, so use subsys_initcall. */
+subsys_initcall(s3c2440_cpufreq_init);
+
+static struct sysdev_driver s3c2442_cpufreq_driver = {
+        .add            = s3c2440_cpufreq_add,
+};
+
+static int s3c2442_cpufreq_init(void)
+{
+        return sysdev_driver_register(&s3c2442_sysclass,
+                                      &s3c2442_cpufreq_driver);
+}
+
+subsys_initcall(s3c2442_cpufreq_init);