ARM: S3C2410: CPUFREQ: Add core support.

Add core support for frequency scaling on the S3C2410 SoC.

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

arch/arm/mach-s3c2410/Kconfig

@@ -12,6 +12,7 @@ config CPU_S3C2410
 	select S3C2410_GPIO
 	select CPU_LLSERIAL_S3C2410
 	select S3C2410_PM if PM
+	select S3C2410_CPUFREQ if CPU_FREQ_S3C24XX
 	help
 	  Support for S3C2410 and S3C2410A family from the S3C24XX line
 	  of Samsung Mobile CPUs.
@@ -45,6 +46,15 @@ config MACH_BAST_IDE
 	  Internal node for machines with an BAST style IDE
 	  interface
 
+# cpu frequency scaling support
+
+config S3C2410_CPUFREQ
+	bool
+	depends on CPU_FREQ_S3C24XX && CPU_S3C2410
+	select S3C2410_CPUFREQ_UTILS
+	help
+	  CPU Frequency scaling support for S3C2410
+
 menu "S3C2410 Machines"
 
 config ARCH_SMDK2410
@@ -79,6 +89,7 @@ config MACH_N30
 config ARCH_BAST
 	bool "Simtec Electronics BAST (EB2410ITX)"
 	select CPU_S3C2410
+	select S3C2410_IOTIMING if S3C2410_CPUFREQ
 	select PM_SIMTEC if PM
 	select SIMTEC_NOR
 	select MACH_BAST_IDE

arch/arm/mach-s3c2410/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_CPU_S3C2410_DMA)	+= dma.o
 obj-$(CONFIG_CPU_S3C2410_DMA)	+= dma.o
 obj-$(CONFIG_S3C2410_PM)	+= pm.o sleep.o
 obj-$(CONFIG_S3C2410_GPIO)	+= gpio.o
+obj-$(CONFIG_S3C2410_CPUFREQ)	+= cpu-freq.o
 
 # Machine support
 

arch/arm/mach-s3c2410/cpu-freq.c

@@ -0,0 +1,157 @@
+/* linux/arch/arm/mach-s3c2410/cpu-freq.c
+ *
+ * Copyright (c) 2006,2008 Simtec Electronics
+ *	http://armlinux.simtec.co.uk/
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C2410 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/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+#include <mach/regs-clock.h>
+
+#include <plat/cpu.h>
+#include <plat/clock.h>
+#include <plat/cpu-freq-core.h>
+
+/* Note, 2410A has an extra mode for 1:4:4 ratio, bit 2 of CLKDIV */
+
+static void s3c2410_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
+{
+	u32 clkdiv = 0;
+
+	if (cfg->divs.h_divisor == 2)
+		clkdiv |= S3C2410_CLKDIVN_HDIVN;
+
+	if (cfg->divs.p_divisor != cfg->divs.h_divisor)
+		clkdiv |= S3C2410_CLKDIVN_PDIVN;
+
+	__raw_writel(clkdiv, S3C2410_CLKDIVN);
+}
+
+static int s3c2410_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
+{
+	unsigned long hclk, fclk, pclk;
+	unsigned int hdiv, pdiv;
+	unsigned long hclk_max;
+
+	fclk = cfg->freq.fclk;
+	hclk_max = cfg->max.hclk;
+
+	cfg->freq.armclk = fclk;
+
+	s3c_freq_dbg("%s: fclk is %lu, max hclk %lu\n",
+		      __func__, fclk, hclk_max);
+
+	hdiv = (fclk > cfg->max.hclk) ? 2 : 1;
+	hclk = fclk / hdiv;
+
+	if (hclk > cfg->max.hclk) {
+		s3c_freq_dbg("%s: hclk too big\n", __func__);
+		return -EINVAL;
+	}
+
+	pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
+	pclk = hclk / pdiv;
+
+	if (pclk > cfg->max.pclk) {
+		s3c_freq_dbg("%s: pclk too big\n", __func__);
+		return -EINVAL;
+	}
+
+	pdiv *= hdiv;
+
+	/* record the result */
+	cfg->divs.p_divisor = pdiv;
+	cfg->divs.h_divisor = hdiv;
+
+	return 0      ;
+}
+
+static struct s3c_cpufreq_info s3c2410_cpufreq_info = {
+	.max		= {
+		.fclk	= 200000000,
+		.hclk	= 100000000,
+		.pclk	=  50000000,
+	},
+
+	/* transition latency is about 5ms worst-case, so
+	 * set 10ms to be sure */
+	.latency	= 10000000,
+
+	.locktime_m	= 150,
+	.locktime_u	= 150,
+	.locktime_bits	= 12,
+
+	.need_pll	= 1,
+
+	.name		= "s3c2410",
+	.calc_iotiming	= s3c2410_iotiming_calc,
+	.set_iotiming	= s3c2410_iotiming_set,
+	.get_iotiming	= s3c2410_iotiming_get,
+	.resume_clocks	= s3c2410_setup_clocks,
+
+	.set_fvco	= s3c2410_set_fvco,
+	.set_refresh	= s3c2410_cpufreq_setrefresh,
+	.set_divs	= s3c2410_cpufreq_setdivs,
+	.calc_divs	= s3c2410_cpufreq_calcdivs,
+};
+
+static int s3c2410_cpufreq_add(struct sys_device *sysdev)
+{
+	return s3c_cpufreq_register(&s3c2410_cpufreq_info);
+}
+
+static struct sysdev_driver s3c2410_cpufreq_driver = {
+	.add		= s3c2410_cpufreq_add,
+};
+
+static int __init s3c2410_cpufreq_init(void)
+{
+	return sysdev_driver_register(&s3c2410_sysclass,
+				      &s3c2410_cpufreq_driver);
+}
+
+arch_initcall(s3c2410_cpufreq_init);
+
+static int s3c2410a_cpufreq_add(struct sys_device *sysdev)
+{
+	/* alter the maximum freq settings for S3C2410A. If a board knows
+	 * it only has a maximum of 200, then it should register its own
+	 * limits. */
+
+	s3c2410_cpufreq_info.max.fclk = 266000000;
+	s3c2410_cpufreq_info.max.hclk = 133000000;
+	s3c2410_cpufreq_info.max.pclk =  66500000;
+	s3c2410_cpufreq_info.name = "s3c2410a";
+
+	return s3c2410_cpufreq_add(sysdev);
+}
+
+static struct sysdev_driver s3c2410a_cpufreq_driver = {
+	.add		= s3c2410a_cpufreq_add,
+};
+
+static int __init s3c2410a_cpufreq_init(void)
+{
+	return sysdev_driver_register(&s3c2410a_sysclass,
+				      &s3c2410a_cpufreq_driver);
+}
+
+arch_initcall(s3c2410a_cpufreq_init);

arch/arm/plat-s3c24xx/Kconfig

@@ -116,6 +116,13 @@ config S3C2410_IOTIMING
 	  Internal node to select io timing code that is common to the s3c2410
 	  and s3c2440/s3c2442 cpu frequency support.
 
+config S3C2410_CPUFREQ_UTILS
+	bool
+	depends on CPU_FREQ_S3C24XX
+	help
+	  Internal node to select timing code that is common to the s3c2410
+	  and s3c2440/s3c244 cpu frequency support.
+
 config MACH_SMDK
 	bool
 	help

arch/arm/plat-s3c24xx/Makefile

@@ -36,6 +36,7 @@ obj-$(CONFIG_S3C2410_CLOCK)	+= s3c2410-clock.o
 obj-$(CONFIG_S3C2410_DMA)	+= dma.o
 obj-$(CONFIG_S3C24XX_ADC)	+= adc.o
 obj-$(CONFIG_S3C2410_IOTIMING)	+= s3c2410-iotiming.o
+obj-$(CONFIG_S3C2410_CPUFREQ_UTILS) += s3c2410-cpufreq-utils.o
 
 # device specific setup and/or initialisation
 obj-$(CONFIG_ARCH_S3C2410)	+= setup-i2c.o

arch/arm/plat-s3c24xx/s3c2410-cpufreq-utils.c

@@ -0,0 +1,64 @@
+/* linux/arch/arm/plat-s3c24xx/s3c2410-cpufreq-utils.c
+ *
+ * Copyright (c) 2009 Simtec Electronics
+ *	http://armlinux.simtec.co.uk/
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C24XX CPU Frequency scaling - utils for S3C2410/S3C2440/S3C2442
+ *
+ * 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/kernel.h>
+#include <linux/errno.h>
+#include <linux/cpufreq.h>
+#include <linux/io.h>
+
+#include <mach/map.h>
+#include <mach/regs-mem.h>
+#include <mach/regs-clock.h>
+
+#include <plat/cpu-freq-core.h>
+
+/**
+ * s3c2410_cpufreq_setrefresh - set SDRAM refresh value
+ * @cfg: The frequency configuration
+ *
+ * Set the SDRAM refresh value appropriately for the configured
+ * frequency.
+ */
+void s3c2410_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)
+{
+	struct s3c_cpufreq_board *board = cfg->board;
+	unsigned long refresh;
+	unsigned long refval;
+
+	/* Reduce both the refresh time (in ns) and the frequency (in MHz)
+	 * down to ensure that we do not overflow 32 bit numbers.
+	 *
+	 * This should work for HCLK up to 133MHz and refresh period up
+	 * to 30usec.
+	 */
+
+	refresh = (cfg->freq.hclk / 100) * (board->refresh / 10);
+	refresh = DIV_ROUND_UP(refresh, (1000 * 1000)); /* apply scale  */
+	refresh = (1 << 11) + 1 - refresh;
+
+	s3c_freq_dbg("%s: refresh value %lu\n", __func__, refresh);
+
+	refval = __raw_readl(S3C2410_REFRESH);
+	refval &= ~((1 << 12) - 1);
+	refval |= refresh;
+	__raw_writel(refval, S3C2410_REFRESH);
+}
+
+/**
+ * s3c2410_set_fvco - set the PLL value
+ * @cfg: The frequency configuration
+ */
+void s3c2410_set_fvco(struct s3c_cpufreq_config *cfg)
+{
+	__raw_writel(cfg->pll.index, S3C2410_MPLLCON);
+}