linux-imx

/*

 * drivers/cpufreq/spear-cpufreq.c

 *

 * CPU Frequency Scaling for SPEAr platform

 *

 * Copyright (C) 2012 ST Microelectronics

 * Deepak Sikri <deepak.sikri@st.com>

 *

 * This file is licensed under the terms of the GNU General Public

 * License version 2. This program is licensed "as is" without any

 * warranty of any kind, whether express or implied.

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/clk.h>

#include <linux/cpufreq.h>

#include <linux/err.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/of_device.h>

#include <linux/platform_device.h>

#include <linux/slab.h>

#include <linux/types.h>

​

/* SPEAr CPUFreq driver data structure */

static struct {

    struct clk *clk;

    unsigned int transition_latency;

    struct cpufreq_frequency_table *freq_tbl;

    u32 cnt;

} spear_cpufreq;

​

static struct clk *spear1340_cpu_get_possible_parent(unsigned long newfreq)

{

    struct clk *sys_pclk;

    int pclk;

    /*

     * In SPEAr1340, cpu clk's parent sys clk can take input from

     * following sources

     */

    const char *sys_clk_src[] = {

        "sys_syn_clk",

        "pll1_clk",

        "pll2_clk",

        "pll3_clk",

    };

​

    /*

     * As sys clk can have multiple source with their own range

     * limitation so we choose possible sources accordingly

     */

    if (newfreq <= 300000000)

        pclk = 0; /* src is sys_syn_clk */

    else if (newfreq > 300000000 && newfreq <= 500000000)

        pclk = 3; /* src is pll3_clk */

    else if (newfreq == 600000000)

        pclk = 1; /* src is pll1_clk */

    else

        return ERR_PTR(-EINVAL);

​

    /* Get parent to sys clock */

    sys_pclk = clk_get(NULL, sys_clk_src[pclk]);

    if (IS_ERR(sys_pclk))

        pr_err("Failed to get %s clock\n", sys_clk_src[pclk]);

​

    return sys_pclk;

}

​

/*

 * In SPEAr1340, we cannot use newfreq directly because we need to actually

 * access a source clock (clk) which might not be ancestor of cpu at present.

 * Hence in SPEAr1340 we would operate on source clock directly before switching

 * cpu clock to it.

 */

static int spear1340_set_cpu_rate(struct clk *sys_pclk, unsigned long newfreq)

{

    struct clk *sys_clk;

    int ret = 0;

​

    sys_clk = clk_get_parent(spear_cpufreq.clk);

    if (IS_ERR(sys_clk)) {

        pr_err("failed to get cpu's parent (sys) clock\n");

        return PTR_ERR(sys_clk);

    }

​

    /* Set the rate of the source clock before changing the parent */

    ret = clk_set_rate(sys_pclk, newfreq);

    if (ret) {

        pr_err("Failed to set sys clk rate to %lu\n", newfreq);

        return ret;

    }