[PATCH] ARM: OMAP: implement CPUfreq frequency table based on PRCM table

Kevin Hilman
2007-11-15T23:38:17Z

This patch adds a CPUfreq frequency-table implementation for OMAP2 by
walking the PRCM rate-table for available entries and adding them to a
CPUfreq table.

CPUfreq can then be used to manage switching between all the available
entries in the PRCM rate table. Either use the CPUfreq sysfs
interface directly, (see Section 3 of Documentation/cpu-freq/user-guide.txt)
or use the cpufrequtils package:
http://www.kernel.org/pub/linux/utils/kernel/cpufreq/cpufrequtils.html

Signed-off-by: Kevin Hilman <khilman@mvista.com>

---
arch/arm/mach-omap2/clock24xx.c | 37 ++++++++++++++++++++++++++++
arch/arm/plat-omap/cpu-omap.c | 52 ++++++++++++++++++++++++++++++++++++++--
2 files changed, 87 insertions(+), 2 deletions(-)

Index: dev/arch/arm/mach-omap2/clock24xx.c
===================================================================
--- dev.orig/arch/arm/mach-omap2/clock24xx.c
+++ dev/arch/arm/mach-omap2/clock24xx.c
@@ -26,6 +26,7 @@
#include <linux/clk.h>

#include <linux/io.h>
+#include <linux/cpufreq.h>

#include <asm/arch/clock.h>
#include <asm/arch/sram.h>
@@ -461,6 +462,42 @@ static int __init omap2_clk_arch_init(vo
}
arch_initcall(omap2_clk_arch_init);

+#ifdef CONFIG_CPU_FREQ
+/*
+ * Walk PRCM rate table and fillout cpufreq freq_table
+ */
+static struct cpufreq_frequency_table freq_table[ARRAY_SIZE(rate_table)];
+
+void clk_init_cpufreq_table(struct cpufreq_frequency_table **table)
+{
+ struct prcm_config *prcm;
+ int i = 0;
+
+ for (prcm = rate_table; prcm->mpu_speed; prcm++) {
+ if (!(prcm->flags & cpu_mask))
+ continue;
+ if (prcm->xtal_speed != sys_ck.rate)
+ continue;
+
+ /* don't put bypass rates in table */
+ if (prcm->dpll_speed == prcm->xtal_speed)
+ continue;
+
+ freq_table[i].index = i;
+ freq_table[i].frequency = prcm->mpu_speed / 1000;
+ i++;
+ }
+
+ freq_table[i].index = i;
+ freq_table[i].frequency = CPUFREQ_TABLE_END;
+
+ *table = &freq_table[0];
+}
+#else
+void clk_init_cpufreq_table(struct cpufreq_frequency_table **table) { }
+#endif
+EXPORT_SYMBOL(clk_init_cpufreq_table);
+
int __init omap2_clk_init(void)
{
struct prcm_config *prcm;
Index: dev/arch/arm/plat-omap/cpu-omap.c
===================================================================
--- dev.orig/arch/arm/plat-omap/cpu-omap.c
+++ dev/arch/arm/plat-omap/cpu-omap.c
@@ -24,12 +24,17 @@
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/system.h>
+#include <asm/arch/clock.h>

#define VERY_HI_RATE 900000000

#ifdef CONFIG_ARCH_OMAP1
#define MPU_CLK "mpu"
#else
+
+#define USE_FREQ_TABLE
+static struct cpufreq_frequency_table *freq_table;
+
#define MPU_CLK "virt_prcm_set"
#endif

@@ -39,6 +44,9 @@ static struct clk *mpu_clk;

int omap_verify_speed(struct cpufreq_policy *policy)
{
+#ifdef USE_FREQ_TABLE
+ return cpufreq_frequency_table_verify(policy, freq_table);
+#else
if (policy->cpu)
return -EINVAL;

@@ -50,6 +58,7 @@ int omap_verify_speed(struct cpufreq_pol
cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
policy->cpuinfo.max_freq);
return 0;
+#endif
}

unsigned int omap_getspeed(unsigned int cpu)
@@ -70,12 +79,26 @@ static int omap_target(struct cpufreq_po
struct cpufreq_freqs freqs;
int ret = 0;

+ /* Ensure desired rate is within allowed range. Some govenors
+ * (ondemand) will just pass target_freq=0 to get the minimum. */
+ if (target_freq < policy->cpuinfo.min_freq)
+ target_freq = policy->cpuinfo.min_freq;
+ if (target_freq > policy->cpuinfo.max_freq)
+ target_freq = policy->cpuinfo.max_freq;
+
freqs.old = omap_getspeed(0);
freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
freqs.cpu = 0;

+ if (freqs.old == freqs.new)
+ return ret;
+
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
- ret = clk_set_rate(mpu_clk, target_freq * 1000);
+#ifdef CONFIG_CPU_FREQ_DEBUG
+ printk(KERN_DEBUG "cpufreq-omap: transition: %u --> %u\n",
+ freqs.old, freqs.new);
+#endif
+ ret = clk_set_rate(mpu_clk, freqs.new * 1000);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

return ret;
@@ -83,16 +106,27 @@ static int omap_target(struct cpufreq_po

static int __init omap_cpu_init(struct cpufreq_policy *policy)
{
+ int result = 0;
+
mpu_clk = clk_get(NULL, MPU_CLK);
if (IS_ERR(mpu_clk))
return PTR_ERR(mpu_clk);

if (policy->cpu != 0)
return -EINVAL;
+
policy->cur = policy->min = policy->max = omap_getspeed(0);
+#ifdef USE_FREQ_TABLE
+ clk_init_cpufreq_table(&freq_table);
+ result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
+ if (!result)
+ cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
+#else
policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
policy->cpuinfo.max_freq = clk_round_rate(mpu_clk, VERY_HI_RATE) / 1000;
- policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
+#endif
+ /* FIXME: what's the actual transition time? */
+ policy->cpuinfo.transition_latency = 10 * 1000 * 1000;

return 0;
}
@@ -103,6 +137,11 @@ static int omap_cpu_exit(struct cpufreq_
return 0;
}

+static struct freq_attr *omap_cpufreq_attr[] = {
+ &cpufreq_freq_attr_scaling_available_freqs,
+ NULL,
+};
+
static struct cpufreq_driver omap_driver = {
.flags = CPUFREQ_STICKY,
.verify = omap_verify_speed,
@@ -111,6 +150,7 @@ static struct cpufreq_driver omap_driver
.init = omap_cpu_init,
.exit = omap_cpu_exit,
.name = "omap",
+ .attr = omap_cpufreq_attr,
};

static int __init omap_cpufreq_init(void)
@@ -119,3 +159,11 @@ static int __init omap_cpufreq_init(void
}

arch_initcall(omap_cpufreq_init);
+
+/*
+ * if ever we want to remove this, upon cleanup call:
+ *
+ * cpufreq_unregister_driver()
+ * cpufreq_frequency_table_put_attr()
+ */
+
--