ARM: S3C2412: CPUFREQ: Add core support.

Add core support for frequency scaling on the S3C2412 SoC.

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

arch/arm/mach-s3c2412/Kconfig

@@ -32,6 +32,12 @@ config S3C2412_PM
 	help
 	  Internal config node to apply S3C2412 power management
 
+config S3C2412_CPUFREQ
+	bool
+	depends on CPU_FREQ_S3C24XX && CPU_S3C2412
+	default y
+	help
+	  CPU Frequency scaling support for S3C2412 and S3C2413 SoC CPUs.
 
 menu "S3C2412 Machines"
 

arch/arm/mach-s3c2412/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_CPU_S3C2412)	+= clock.o
 obj-$(CONFIG_CPU_S3C2412)	+= gpio.o
 obj-$(CONFIG_S3C2412_DMA)	+= dma.o
 obj-$(CONFIG_S3C2412_PM)	+= pm.o sleep.o
+obj-$(CONFIG_S3C2412_CPUFREQ)	+= cpu-freq.o
 
 # Machine support
 

arch/arm/mach-s3c2412/cpu-freq.c

@@ -0,0 +1,251 @@
+/* linux/arch/arm/mach-s3c2412/cpu-freq.c
+ *
+ * Copyright 2008 Simtec Electronics
+ *	http://armlinux.simtec.co.uk/
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C2412 CPU Frequency scalling
+ *
+ * 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 <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+#include <mach/regs-clock.h>
+#include <mach/regs-s3c2412-mem.h>
+
+#include <plat/cpu.h>
+#include <plat/clock.h>
+#include <plat/cpu-freq-core.h>
+
+/* our clock resources. */
+static struct clk *xtal;
+static struct clk *fclk;
+static struct clk *hclk;
+static struct clk *armclk;
+
+/* HDIV: 1, 2, 3, 4, 6, 8 */
+
+static int s3c2412_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
+{
+	unsigned int hdiv, pdiv, armdiv, dvs;
+	unsigned long hclk, fclk, armclk, armdiv_clk;
+	unsigned long hclk_max;
+
+	fclk = cfg->freq.fclk;
+	armclk = cfg->freq.armclk;
+	hclk_max = cfg->max.hclk;
+
+	/* We can't run hclk above armclk as at the best we have to
+	 * have armclk and hclk in dvs mode. */
+
+	if (hclk_max > armclk)
+		hclk_max = armclk;
+
+	s3c_freq_dbg("%s: fclk=%lu, armclk=%lu, hclk_max=%lu\n",
+		     __func__, fclk, armclk, hclk_max);
+	s3c_freq_dbg("%s: want f=%lu, arm=%lu, h=%lu, p=%lu\n",
+		     __func__, cfg->freq.fclk, cfg->freq.armclk,
+		     cfg->freq.hclk, cfg->freq.pclk);
+
+	armdiv = fclk / armclk;
+
+	if (armdiv < 1)
+		armdiv = 1;
+	if (armdiv > 2)
+		armdiv = 2;
+
+	cfg->divs.arm_divisor = armdiv;
+	armdiv_clk = fclk / armdiv;
+
+	hdiv = armdiv_clk / hclk_max;
+	if (hdiv < 1)
+		hdiv = 1;
+
+	cfg->freq.hclk = hclk = armdiv_clk / hdiv;
+
+	/* set dvs depending on whether we reached armclk or not. */
+	cfg->divs.dvs = dvs = armclk < armdiv_clk;
+
+	/* update the actual armclk we achieved. */
+	cfg->freq.armclk = dvs ? hclk : armdiv_clk;
+
+	s3c_freq_dbg("%s: armclk %lu, hclk %lu, armdiv %d, hdiv %d, dvs %d\n",
+		     __func__, armclk, hclk, armdiv, hdiv, cfg->divs.dvs);
+
+	if (hdiv > 4)
+		goto invalid;
+
+	pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
+
+	if ((hclk / pdiv) > cfg->max.pclk)
+		pdiv++;
+
+	cfg->freq.pclk = hclk / pdiv;
+
+	s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);
+
+	if (pdiv > 2)
+		goto invalid;
+
+	pdiv *= hdiv;
+
+	/* store the result, and then return */
+
+	cfg->divs.h_divisor = hdiv * armdiv;
+	cfg->divs.p_divisor = pdiv * armdiv;
+
+	return 0;
+
+ invalid:
+	return -EINVAL;
+}
+
+static void s3c2412_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
+{
+	unsigned long clkdiv;
+	unsigned long olddiv;
+
+	olddiv = clkdiv = __raw_readl(S3C2410_CLKDIVN);
+
+	/* clear off current clock info */
+
+	clkdiv &= ~S3C2412_CLKDIVN_ARMDIVN;
+	clkdiv &= ~S3C2412_CLKDIVN_HDIVN_MASK;
+	clkdiv &= ~S3C2412_CLKDIVN_PDIVN;
+
+	if (cfg->divs.arm_divisor == 2)
+		clkdiv |= S3C2412_CLKDIVN_ARMDIVN;
+
+	clkdiv |= ((cfg->divs.h_divisor / cfg->divs.arm_divisor) - 1);
+
+	if (cfg->divs.p_divisor != cfg->divs.h_divisor)
+		clkdiv |= S3C2412_CLKDIVN_PDIVN;
+
+	s3c_freq_dbg("%s: div %08lx => %08lx\n", __func__, olddiv, clkdiv);
+	__raw_writel(clkdiv, S3C2410_CLKDIVN);
+
+	clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);
+}
+
+static void s3c2412_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)
+{
+	struct s3c_cpufreq_board *board = cfg->board;
+	unsigned long refresh;
+
+	s3c_freq_dbg("%s: refresh %u ns, hclk %lu\n", __func__,
+		     board->refresh, cfg->freq.hclk);
+
+	/* Reduce both the refresh time (in ns) and the frequency (in MHz)
+	 * by 10 each 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 = (board->refresh / 10);
+	refresh *= (cfg->freq.hclk / 100);
+	refresh /= (1 * 1000 * 1000);	/* 10^6 */
+
+	s3c_freq_dbg("%s: setting refresh 0x%08lx\n", __func__, refresh);
+	__raw_writel(refresh, S3C2412_REFRESH);
+}
+
+/* set the default cpu frequency information, based on an 200MHz part
+ * as we have no other way of detecting the speed rating in software.
+ */
+
+static struct s3c_cpufreq_info s3c2412_cpufreq_info = {
+	.max		= {
+		.fclk	= 200000000,
+		.hclk	= 100000000,
+		.pclk	=  50000000,
+	},
+
+	.latency	= 5000000, /* 5ms */
+
+	.locktime_m	= 150,
+	.locktime_u	= 150,
+	.locktime_bits	= 16,
+
+	.name		= "s3c2412",
+	.set_refresh	= s3c2412_cpufreq_setrefresh,
+	.set_divs	= s3c2412_cpufreq_setdivs,
+	.calc_divs	= s3c2412_cpufreq_calcdivs,
+
+	.resume_clocks	= s3c2412_setup_clocks,
+};
+
+static int s3c2412_cpufreq_add(struct sys_device *sysdev)
+{
+	unsigned long fclk_rate;
+
+	hclk = clk_get(NULL, "hclk");
+	if (IS_ERR(hclk)) {
+		printk(KERN_ERR "%s: cannot find hclk clock\n", __func__);
+		return -ENOENT;
+	}
+
+	fclk = clk_get(NULL, "fclk");
+	if (IS_ERR(fclk)) {
+		printk(KERN_ERR "%s: cannot find fclk clock\n", __func__);
+		goto err_fclk;
+	}
+
+	fclk_rate = clk_get_rate(fclk);
+	if (fclk_rate > 200000000) {
+		printk(KERN_INFO
+		       "%s: fclk %ld MHz, assuming 266MHz capable part\n",
+		       __func__, fclk_rate / 1000000);
+		s3c2412_cpufreq_info.max.fclk = 266000000;
+		s3c2412_cpufreq_info.max.hclk = 133000000;
+		s3c2412_cpufreq_info.max.pclk =  66000000;
+	}
+
+	armclk = clk_get(NULL, "armclk");
+	if (IS_ERR(armclk)) {
+		printk(KERN_ERR "%s: cannot find arm clock\n", __func__);
+		goto err_armclk;
+	}
+
+	xtal = clk_get(NULL, "xtal");
+	if (IS_ERR(xtal)) {
+		printk(KERN_ERR "%s: cannot find xtal clock\n", __func__);
+		goto err_xtal;
+	}
+
+	return s3c_cpufreq_register(&s3c2412_cpufreq_info);
+
+err_xtal:
+	clk_put(armclk);
+err_armclk:
+	clk_put(fclk);
+err_fclk:
+	clk_put(hclk);
+
+	return -ENOENT;
+}
+
+static struct sysdev_driver s3c2412_cpufreq_driver = {
+	.add		= s3c2412_cpufreq_add,
+};
+
+static int s3c2412_cpufreq_init(void)
+{
+	return sysdev_driver_register(&s3c2412_sysclass,
+				      &s3c2412_cpufreq_driver);
+}
+
+arch_initcall(s3c2412_cpufreq_init);