cpufreq for freescale mx51

Currently, only two operating points: 160Mhz and 800Mhz.
the operating points are tested on babbage 3.0

Signed-off-by: Yong Shen <yong.shen@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/Kconfig

@@ -1584,6 +1584,12 @@ if ARCH_HAS_CPUFREQ
 
 source "drivers/cpufreq/Kconfig"
 
+config CPU_FREQ_IMX
+	tristate "CPUfreq driver for i.MX CPUs"
+	depends on ARCH_MXC && CPU_FREQ
+	help
+	  This enables the CPUfreq driver for i.MX CPUs.
+
 config CPU_FREQ_SA1100
 	bool
 

arch/arm/mach-mx5/Kconfig

@@ -6,6 +6,7 @@ config ARCH_MX51
 	select MXC_TZIC
 	select ARCH_MXC_IOMUX_V3
 	select ARCH_MXC_AUDMUX_V2
+	select ARCH_HAS_CPUFREQ
 
 comment "MX5 platforms:"
 

arch/arm/mach-mx5/Makefile

@@ -5,6 +5,7 @@
 # Object file lists.
 obj-y   := cpu.o mm.o clock-mx51.o devices.o
 
+obj-$(CONFIG_CPU_FREQ_IMX)    += cpu_op-mx51.o
 obj-$(CONFIG_MACH_MX51_BABBAGE) += board-mx51_babbage.o
 obj-$(CONFIG_MACH_MX51_3DS) += board-mx51_3ds.o
 obj-$(CONFIG_MACH_EUKREA_CPUIMX51) += board-cpuimx51.o

arch/arm/mach-mx5/board-mx51_babbage.c

@@ -1,5 +1,5 @@
 /*
- * Copyright 2009 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
  * Copyright (C) 2009-2010 Amit Kucheria <amit.kucheria@canonical.com>
  *
  * The code contained herein is licensed under the GNU General Public
@@ -32,6 +32,7 @@
 
 #include "devices-imx51.h"
 #include "devices.h"
+#include "cpu_op-mx51.h"
 
 #define BABBAGE_USB_HUB_RESET	(0*32 + 7)	/* GPIO_1_7 */
 #define BABBAGE_USBH1_STP	(0*32 + 27)	/* GPIO_1_27 */
@@ -298,6 +299,9 @@ static void __init mxc_board_init(void)
 {
 	struct pad_desc usbh1stp = MX51_PAD_USBH1_STP__USBH1_STP;
 
+#if defined(CONFIG_CPU_FREQ_IMX)
+	get_cpu_op = mx51_get_cpu_op;
+#endif
 	mxc_iomux_v3_setup_multiple_pads(mx51babbage_pads,
 					ARRAY_SIZE(mx51babbage_pads));
 	mxc_init_imx_uart();

arch/arm/mach-mx5/clock-mx51.c

@@ -362,7 +362,7 @@ static int _clk_lp_apm_set_parent(struct clk *clk, struct clk *parent)
 	return 0;
 }
 
-static unsigned long clk_arm_get_rate(struct clk *clk)
+static unsigned long clk_cpu_get_rate(struct clk *clk)
 {
 	u32 cacrr, div;
 	unsigned long parent_rate;
@@ -374,6 +374,22 @@ static unsigned long clk_arm_get_rate(struct clk *clk)
 	return parent_rate / div;
 }
 
+static int clk_cpu_set_rate(struct clk *clk, unsigned long rate)
+{
+	u32 reg, cpu_podf;
+	unsigned long parent_rate;
+
+	parent_rate = clk_get_rate(clk->parent);
+	cpu_podf = parent_rate / rate - 1;
+	/* use post divider to change freq */
+	reg = __raw_readl(MXC_CCM_CACRR);
+	reg &= ~MXC_CCM_CACRR_ARM_PODF_MASK;
+	reg |= cpu_podf << MXC_CCM_CACRR_ARM_PODF_OFFSET;
+	__raw_writel(reg, MXC_CCM_CACRR);
+
+	return 0;
+}
+
 static int _clk_periph_apm_set_parent(struct clk *clk, struct clk *parent)
 {
 	u32 reg, mux;
@@ -736,7 +752,8 @@ static struct clk periph_apm_clk = {
 
 static struct clk cpu_clk = {
 	.parent = &pll1_sw_clk,
-	.get_rate = clk_arm_get_rate,
+	.get_rate = clk_cpu_get_rate,
+	.set_rate = clk_cpu_set_rate,
 };
 
 static struct clk ahb_clk = {
@@ -1064,6 +1081,7 @@ static struct clk_lookup lookups[] = {
 	_REGISTER_CLOCK("imx51-cspi.0", NULL, cspi_clk)
 	_REGISTER_CLOCK("sdhci-esdhc-imx.0", NULL, esdhc1_clk)
 	_REGISTER_CLOCK("sdhci-esdhc-imx.1", NULL, esdhc2_clk)
+	_REGISTER_CLOCK(NULL, "cpu_clk", cpu_clk)
 };
 
 static void clk_tree_init(void)

arch/arm/mach-mx5/cpu_op-mx51.c

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#include <linux/types.h>
+#include <mach/hardware.h>
+#include <linux/kernel.h>
+
+static struct cpu_op mx51_cpu_op[] = {
+	{
+	.cpu_rate = 160000000,},
+	{
+	.cpu_rate = 800000000,},
+};
+
+struct cpu_op *mx51_get_cpu_op(int *op)
+{
+	*op = ARRAY_SIZE(mx51_cpu_op);
+	return mx51_cpu_op;
+}

arch/arm/mach-mx5/cpu_op-mx51.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+extern struct cpu_op *mx51_get_cpu_op(int *op);

arch/arm/plat-mxc/Makefile

@@ -18,6 +18,7 @@ obj-$(CONFIG_MXC_USE_EPIT) += epit.o
 obj-$(CONFIG_ARCH_MXC_AUDMUX_V1) += audmux-v1.o
 obj-$(CONFIG_ARCH_MXC_AUDMUX_V2) += audmux-v2.o
 obj-$(CONFIG_MXC_DEBUG_BOARD) += 3ds_debugboard.o
+obj-$(CONFIG_CPU_FREQ_IMX)    += cpufreq.o
 ifdef CONFIG_SND_IMX_SOC
 obj-y += ssi-fiq.o
 obj-y += ssi-fiq-ksym.o

arch/arm/plat-mxc/cpufreq.c

@@ -0,0 +1,206 @@
+/*
+ * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+/*
+ * A driver for the Freescale Semiconductor i.MXC CPUfreq module.
+ * The CPUFREQ driver is for controling CPU frequency. It allows you to change
+ * the CPU clock speed on the fly.
+ */
+
+#include <linux/cpufreq.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <mach/hardware.h>
+#include <mach/clock.h>
+
+#define CLK32_FREQ	32768
+#define NANOSECOND	(1000 * 1000 * 1000)
+
+struct cpu_op *(*get_cpu_op)(int *op);
+
+static int cpu_freq_khz_min;
+static int cpu_freq_khz_max;
+
+static struct clk *cpu_clk;
+static struct cpufreq_frequency_table *imx_freq_table;
+
+static int cpu_op_nr;
+static struct cpu_op *cpu_op_tbl;
+
+static int set_cpu_freq(int freq)
+{
+	int ret = 0;
+	int org_cpu_rate;
+
+	org_cpu_rate = clk_get_rate(cpu_clk);
+	if (org_cpu_rate == freq)
+		return ret;
+
+	ret = clk_set_rate(cpu_clk, freq);
+	if (ret != 0) {
+		printk(KERN_DEBUG "cannot set CPU clock rate\n");
+		return ret;
+	}
+
+	return ret;
+}
+
+static int mxc_verify_speed(struct cpufreq_policy *policy)
+{
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	return cpufreq_frequency_table_verify(policy, imx_freq_table);
+}
+
+static unsigned int mxc_get_speed(unsigned int cpu)
+{
+	if (cpu)
+		return 0;
+
+	return clk_get_rate(cpu_clk) / 1000;
+}
+
+static int mxc_set_target(struct cpufreq_policy *policy,
+			  unsigned int target_freq, unsigned int relation)
+{
+	struct cpufreq_freqs freqs;
+	int freq_Hz;
+	int ret = 0;
+	unsigned int index;
+
+	cpufreq_frequency_table_target(policy, imx_freq_table,
+			target_freq, relation, &index);
+	freq_Hz = imx_freq_table[index].frequency * 1000;
+
+	freqs.old = clk_get_rate(cpu_clk) / 1000;
+	freqs.new = freq_Hz / 1000;
+	freqs.cpu = 0;
+	freqs.flags = 0;
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+	ret = set_cpu_freq(freq_Hz);
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	return ret;
+}
+
+static int __init mxc_cpufreq_init(struct cpufreq_policy *policy)
+{
+	int ret;
+	int i;
+
+	printk(KERN_INFO "i.MXC CPU frequency driver\n");
+
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	if (!get_cpu_op)
+		return -EINVAL;
+
+	cpu_clk = clk_get(NULL, "cpu_clk");
+	if (IS_ERR(cpu_clk)) {
+		printk(KERN_ERR "%s: failed to get cpu clock\n", __func__);
+		return PTR_ERR(cpu_clk);
+	}
+
+	cpu_op_tbl = get_cpu_op(&cpu_op_nr);
+
+	cpu_freq_khz_min = cpu_op_tbl[0].cpu_rate / 1000;
+	cpu_freq_khz_max = cpu_op_tbl[0].cpu_rate / 1000;
+
+	imx_freq_table = kmalloc(
+		sizeof(struct cpufreq_frequency_table) * (cpu_op_nr + 1),
+			GFP_KERNEL);
+	if (!imx_freq_table) {
+		ret = -ENOMEM;
+		goto err1;
+	}
+
+	for (i = 0; i < cpu_op_nr; i++) {
+		imx_freq_table[i].index = i;
+		imx_freq_table[i].frequency = cpu_op_tbl[i].cpu_rate / 1000;
+
+		if ((cpu_op_tbl[i].cpu_rate / 1000) < cpu_freq_khz_min)
+			cpu_freq_khz_min = cpu_op_tbl[i].cpu_rate / 1000;
+
+		if ((cpu_op_tbl[i].cpu_rate / 1000) > cpu_freq_khz_max)
+			cpu_freq_khz_max = cpu_op_tbl[i].cpu_rate / 1000;
+	}
+
+	imx_freq_table[i].index = i;
+	imx_freq_table[i].frequency = CPUFREQ_TABLE_END;
+
+	policy->cur = clk_get_rate(cpu_clk) / 1000;
+	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+	policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min;
+	policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max;
+
+	/* Manual states, that PLL stabilizes in two CLK32 periods */
+	policy->cpuinfo.transition_latency = 2 * NANOSECOND / CLK32_FREQ;
+
+	ret = cpufreq_frequency_table_cpuinfo(policy, imx_freq_table);
+
+	if (ret < 0) {
+		printk(KERN_ERR "%s: failed to register i.MXC CPUfreq \
+				with error code %d\n", __func__, ret);
+		goto err;
+	}
+
+	cpufreq_frequency_table_get_attr(imx_freq_table, policy->cpu);
+	return 0;
+err:
+	kfree(imx_freq_table);
+err1:
+	clk_put(cpu_clk);
+	return ret;
+}
+
+static int mxc_cpufreq_exit(struct cpufreq_policy *policy)
+{
+	cpufreq_frequency_table_put_attr(policy->cpu);
+
+	set_cpu_freq(cpu_freq_khz_max * 1000);
+	clk_put(cpu_clk);
+	kfree(imx_freq_table);
+	return 0;
+}
+
+static struct cpufreq_driver mxc_driver = {
+	.flags = CPUFREQ_STICKY,
+	.verify = mxc_verify_speed,
+	.target = mxc_set_target,
+	.get = mxc_get_speed,
+	.init = mxc_cpufreq_init,
+	.exit = mxc_cpufreq_exit,
+	.name = "imx",
+};
+
+static int __devinit mxc_cpufreq_driver_init(void)
+{
+	return cpufreq_register_driver(&mxc_driver);
+}
+
+static void mxc_cpufreq_driver_exit(void)
+{
+	cpufreq_unregister_driver(&mxc_driver);
+}
+
+module_init(mxc_cpufreq_driver_init);
+module_exit(mxc_cpufreq_driver_exit);
+
+MODULE_AUTHOR("Freescale Semiconductor Inc. Yong Shen <yong.shen@linaro.org>");
+MODULE_DESCRIPTION("CPUfreq driver for i.MX");
+MODULE_LICENSE("GPL");

arch/arm/plat-mxc/include/mach/mxc.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2004-2007 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2004-2007, 2010 Freescale Semiconductor, Inc. All Rights Reserved.
  * Copyright (C) 2008 Juergen Beisert (kernel@pengutronix.de)
  *
  * This program is free software; you can redistribute it and/or
@@ -20,6 +20,8 @@
 #ifndef __ASM_ARCH_MXC_H__
 #define __ASM_ARCH_MXC_H__
 
+#include <linux/types.h>
+
 #ifndef __ASM_ARCH_MXC_HARDWARE_H__
 #error "Do not include directly."
 #endif
@@ -133,6 +135,15 @@ extern unsigned int __mxc_cpu_type;
 # define cpu_is_mxc91231()	(0)
 #endif
 
+#ifndef __ASSEMBLY__
+
+struct cpu_op {
+	u32 cpu_rate;
+};
+
+extern struct cpu_op *(*get_cpu_op)(int *op);
+#endif
+
 #if defined(CONFIG_ARCH_MX3) || defined(CONFIG_ARCH_MX2)
 /* These are deprecated, use mx[23][157]_setup_weimcs instead. */
 #define CSCR_U(n) (IO_ADDRESS(WEIM_BASE_ADDR + n * 0x10))