> +#include <linux/kernel.h>
> +
> +static struct cpu_op mx51_cpu_op[] = {
> +     {
> +     .cpu_rate = 160000000,},
> +     {
> +     .cpu_rate = 800000000,},
> +};

Why did you remove the values between 800MHz and 160MHz? 400MHz and
200Mhz should work also, no?

> +
> +struct cpu_op *mx51_get_cpu_op(int *op)
> +{
> +     *op = ARRAY_SIZE(mx51_cpu_op);
> +     return mx51_cpu_op;
> +}
> diff --git a/arch/arm/mach-mx5/cpu_op-mx51.h b/arch/arm/mach-mx5/cpu_op-mx51.h
> new file mode 100644
> index 0000000..97477fe
> --- /dev/null
> +++ b/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);
> diff --git a/arch/arm/plat-mxc/Makefile b/arch/arm/plat-mxc/Makefile
> index 78d405e..a833d38 100644
> --- a/arch/arm/plat-mxc/Makefile
> +++ b/arch/arm/plat-mxc/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_MXC_ULPI) += ulpi.o
>  obj-$(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
> diff --git a/arch/arm/plat-mxc/cpufreq.c b/arch/arm/plat-mxc/cpufreq.c
> new file mode 100644
> index 0000000..9cabeb9
> --- /dev/null
> +++ b/arch/arm/plat-mxc/cpufreq.c
> @@ -0,0 +1,202 @@
> +/*
> + * 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)
> +
> +static int cpu_freq_khz_min;
> +static int cpu_freq_khz_max;
> +static int arm_normal_clk;
> +
> +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;

You already checked this in mxc_set_target. Once is enough.

> +
> +     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);
> +
> +     if (freqs.old != freqs.new)
> +             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;
> +
> +     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);

This will crash every board except the babbage board which happens to
set this function pointer.