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 a547c79ed6ce..feb9db8886be 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 b28fe9cb0e5e..b73f2e17b166 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 000000000000..c177a20319e2
--- /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);