[ARM] pxa: add cpufreq support

There have been patches hanging around for ages to add support for
cpufreq to PXA255 processors.  It's about time we applied one.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 294 insertions, 0 deletions

diff --git a/arch/arm/mach-pxa/Makefile b/arch/arm/mach-pxa/Makefile
index 4263527e5123..3133dc4eaa7e 100644
--- a/arch/arm/mach-pxa/Makefile
+++ b/arch/arm/mach-pxa/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_LEDS)		+= $(led-y)
 
 # Misc features
 obj-$(CONFIG_PM)                += pm.o sleep.o
+obj-$(CONFIG_CPU_FREQ)          += cpu-pxa.o
 obj-$(CONFIG_PXA_SSP)           += ssp.o
 
 ifeq ($(CONFIG_PXA27x),y)
diff --git a/arch/arm/mach-pxa/cpu-pxa.c b/arch/arm/mach-pxa/cpu-pxa.c
new file mode 100644
index 000000000000..18d042bdf243
--- /dev/null
+++ b/arch/arm/mach-pxa/cpu-pxa.c
@@ -0,0 +1,293 @@
+/*
+ *  linux/arch/arm/mach-pxa/cpu-pxa.c
+ *
+ *  Copyright (C) 2002,2003 Intrinsyc Software
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * History:
+ *   31-Jul-2002 : Initial version [FB]
+ *   29-Jan-2003 : added PXA255 support [FB]
+ *   20-Apr-2003 : ported to v2.5 (Dustin McIntire, Sensoria Corp.)
+ *
+ * Note:
+ *   This driver may change the memory bus clock rate, but will not do any
+ *   platform specific access timing changes... for example if you have flash
+ *   memory connected to CS0, you will need to register a platform specific
+ *   notifier which will adjust the memory access strobes to maintain a
+ *   minimum strobe width.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+
+#include <asm/hardware.h>
+#include <asm/arch/pxa-regs.h>
+
+#ifdef DEBUG
+static unsigned int freq_debug;
+MODULE_PARM(freq_debug, "i");
+MODULE_PARM_DESC(freq_debug, "Set the debug messages to on=1/off=0");
+#else
+#define freq_debug  0
+#endif
+
+typedef struct {
+        unsigned int khz;
+        unsigned int membus;
+        unsigned int cccr;
+        unsigned int div2;
+} pxa_freqs_t;
+
+/* Define the refresh period in mSec for the SDRAM and the number of rows */
+#define SDRAM_TREF          64      /* standard 64ms SDRAM */
+#define SDRAM_ROWS          4096    /* 64MB=8192 32MB=4096 */
+#define MDREFR_DRI(x)       (((x) * SDRAM_TREF) / (SDRAM_ROWS * 32))
+
+#define CCLKCFG_TURBO       0x1
+#define CCLKCFG_FCS         0x2
+#define PXA25x_MIN_FREQ     99500
+#define PXA25x_MAX_FREQ     398100
+#define MDREFR_DB2_MASK     (MDREFR_K2DB2 | MDREFR_K1DB2)
+#define MDREFR_DRI_MASK     0xFFF
+
+
+/* Use the run mode frequencies for the CPUFREQ_POLICY_PERFORMANCE policy */
+static pxa_freqs_t pxa255_run_freqs[] =
+{
+    /* CPU   MEMBUS  CCCR  DIV2*/
+    { 99500,  99500, 0x121, 1}, /* run= 99, turbo= 99, PXbus=50,  SDRAM=50 */
+    {132700, 132700, 0x123, 1}, /* run=133, turbo=133, PXbus=66,  SDRAM=66 */
+    {199100,  99500, 0x141, 0}, /* run=199, turbo=199, PXbus=99,  SDRAM=99 */
+    {265400, 132700, 0x143, 1}, /* run=265, turbo=265, PXbus=133, SDRAM=66 */
+    {331800, 165900, 0x145, 1}, /* run=331, turbo=331, PXbus=166, SDRAM=83 */
+    {398100,  99500, 0x161, 0}, /* run=398, turbo=398, PXbus=196, SDRAM=99 */
+    {0,}
+};
+#define NUM_RUN_FREQS ARRAY_SIZE(pxa255_run_freqs)
+
+static struct cpufreq_frequency_table pxa255_run_freq_table[NUM_RUN_FREQS+1];
+
+/* Use the turbo mode frequencies for the CPUFREQ_POLICY_POWERSAVE policy */
+static pxa_freqs_t pxa255_turbo_freqs[] =
+{
+    /* CPU   MEMBUS  CCCR  DIV2*/
+    { 99500, 99500,  0x121, 1}, /* run=99,  turbo= 99, PXbus=50, SDRAM=50 */
+    {199100, 99500,  0x221, 0}, /* run=99,  turbo=199, PXbus=50, SDRAM=99 */
+    {298500, 99500,  0x321, 0}, /* run=99,  turbo=287, PXbus=50, SDRAM=99 */
+    {298600, 99500,  0x1c1, 0}, /* run=199, turbo=287, PXbus=99, SDRAM=99 */
+    {398100, 99500,  0x241, 0}, /* run=199, turbo=398, PXbus=99, SDRAM=99 */
+    {0,}
+};
+#define NUM_TURBO_FREQS ARRAY_SIZE(pxa255_turbo_freqs)
+
+static struct cpufreq_frequency_table pxa255_turbo_freq_table[NUM_TURBO_FREQS+1];
+
+extern unsigned get_clk_frequency_khz(int info);
+
+/* find a valid frequency point */
+static int pxa_verify_policy(struct cpufreq_policy *policy)
+{
+        struct cpufreq_frequency_table *pxa_freqs_table;
+        int ret;
+
+        if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
+                pxa_freqs_table = pxa255_run_freq_table;
+        } else if (policy->policy == CPUFREQ_POLICY_POWERSAVE) {
+                pxa_freqs_table = pxa255_turbo_freq_table;
+        } else {
+                printk("CPU PXA: Unknown policy found. "
+                       "Using CPUFREQ_POLICY_PERFORMANCE\n");
+                pxa_freqs_table = pxa255_run_freq_table;
+        }
+
+        ret = cpufreq_frequency_table_verify(policy, pxa_freqs_table);
+
+        if (freq_debug)
+                pr_debug("Verified CPU policy: %dKhz min to %dKhz max\n",
+                       policy->min, policy->max);
+
+        return ret;
+}
+
+static int pxa_set_target(struct cpufreq_policy *policy,
+                           unsigned int target_freq,
+                           unsigned int relation)
+{
+        struct cpufreq_frequency_table *pxa_freqs_table;
+        pxa_freqs_t *pxa_freq_settings;
+        struct cpufreq_freqs freqs;
+        int idx;
+        unsigned long flags;
+        unsigned int unused, preset_mdrefr, postset_mdrefr;
+        void *ramstart = phys_to_virt(0xa0000000);
+
+        /* Get the current policy */
+        if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
+                pxa_freq_settings = pxa255_run_freqs;
+                pxa_freqs_table   = pxa255_run_freq_table;
+        } else if (policy->policy == CPUFREQ_POLICY_POWERSAVE) {
+                pxa_freq_settings = pxa255_turbo_freqs;
+                pxa_freqs_table   = pxa255_turbo_freq_table;
+        } else {
+                printk("CPU PXA: Unknown policy found. "
+                       "Using CPUFREQ_POLICY_PERFORMANCE\n");
+                pxa_freq_settings = pxa255_run_freqs;
+                pxa_freqs_table   = pxa255_run_freq_table;
+        }
+
+        /* Lookup the next frequency */
+        if (cpufreq_frequency_table_target(policy, pxa_freqs_table,
+                                           target_freq, relation, &idx)) {
+                return -EINVAL;
+        }
+
+        freqs.old = policy->cur;
+        freqs.new = pxa_freq_settings[idx].khz;
+        freqs.cpu = policy->cpu;
+
+        if (freq_debug)
+                pr_debug(KERN_INFO "Changing CPU frequency to %d Mhz, (SDRAM %d Mhz)\n",
+                       freqs.new / 1000, (pxa_freq_settings[idx].div2) ?
+                       (pxa_freq_settings[idx].membus / 2000) :
+                       (pxa_freq_settings[idx].membus / 1000));
+
+        /*
+         * Tell everyone what we're about to do...
+         * you should add a notify client with any platform specific
+         * Vcc changing capability
+         */
+        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+        /* Calculate the next MDREFR.  If we're slowing down the SDRAM clock
+         * we need to preset the smaller DRI before the change.  If we're speeding
+         * up we need to set the larger DRI value after the change.
+         */
+        preset_mdrefr = postset_mdrefr = MDREFR;
+        if ((MDREFR & MDREFR_DRI_MASK) > MDREFR_DRI(pxa_freq_settings[idx].membus)) {
+                preset_mdrefr = (preset_mdrefr & ~MDREFR_DRI_MASK) |
+                                MDREFR_DRI(pxa_freq_settings[idx].membus);
+        }
+        postset_mdrefr = (postset_mdrefr & ~MDREFR_DRI_MASK) |
+                            MDREFR_DRI(pxa_freq_settings[idx].membus);
+
+        /* If we're dividing the memory clock by two for the SDRAM clock, this
+         * must be set prior to the change.  Clearing the divide must be done
+         * after the change.
+         */
+        if (pxa_freq_settings[idx].div2) {
+                preset_mdrefr  |= MDREFR_DB2_MASK;
+                postset_mdrefr |= MDREFR_DB2_MASK;
+        } else {
+                postset_mdrefr &= ~MDREFR_DB2_MASK;
+        }
+
+        local_irq_save(flags);
+
+        /* Set new the CCCR */
+        CCCR = pxa_freq_settings[idx].cccr;
+
+        asm volatile("                                                  \n\
+                ldr     r4, [%1]                /* load MDREFR */       \n\
+                b       2f                                              \n\
+                .align  5                                               \n\
+1:                                                                      \n\
+                str     %4, [%1]                /* preset the MDREFR */ \n\
+                mcr     p14, 0, %2, c6, c0, 0   /* set CCLKCFG[FCS] */  \n\
+                str     %5, [%1]                /* postset the MDREFR */ \n\
+                                                                        \n\
+                b       3f                                              \n\
+2:              b       1b                                              \n\
+3:              nop                                                     \n\
+          "
+          : "=&r" (unused)
+          : "r" (&MDREFR), "r" (CCLKCFG_TURBO|CCLKCFG_FCS), "r" (ramstart),
+            "r" (preset_mdrefr), "r" (postset_mdrefr)
+          : "r4", "r5");
+        local_irq_restore(flags);
+
+        /*
+         * Tell everyone what we've just done...
+         * you should add a notify client with any platform specific
+         * SDRAM refresh timer adjustments
+         */
+        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+        return 0;
+}
+
+static int pxa_cpufreq_init(struct cpufreq_policy *policy)
+{
+        int i;
+
+        /* set default policy and cpuinfo */
+        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+        policy->policy = CPUFREQ_POLICY_PERFORMANCE;
+        policy->cpuinfo.max_freq = PXA25x_MAX_FREQ;
+        policy->cpuinfo.min_freq = PXA25x_MIN_FREQ;
+        policy->cpuinfo.transition_latency = 1000; /* FIXME: 1 ms, assumed */
+        policy->cur = get_clk_frequency_khz(0);    /* current freq */
+        policy->min = policy->max = policy->cur;
+
+        /* Generate the run cpufreq_frequency_table struct */
+        for (i = 0; i < NUM_RUN_FREQS; i++) {
+                pxa255_run_freq_table[i].frequency = pxa255_run_freqs[i].khz;
+                pxa255_run_freq_table[i].index = i;
+        }
+
+        pxa255_run_freq_table[i].frequency = CPUFREQ_TABLE_END;
+        /* Generate the turbo cpufreq_frequency_table struct */
+        for (i = 0; i < NUM_TURBO_FREQS; i++) {
+                pxa255_turbo_freq_table[i].frequency = pxa255_turbo_freqs[i].khz;
+                pxa255_turbo_freq_table[i].index = i;
+        }
+        pxa255_turbo_freq_table[i].frequency = CPUFREQ_TABLE_END;
+
+        printk(KERN_INFO "PXA CPU frequency change support initialized\n");
+
+        return 0;
+}
+
+static struct cpufreq_driver pxa_cpufreq_driver = {
+        .verify = pxa_verify_policy,
+        .target = pxa_set_target,
+        .init   = pxa_cpufreq_init,
+        .name   = "PXA25x",
+};
+
+static int __init pxa_cpu_init(void)
+{
+        int ret = -ENODEV;
+        if (cpu_is_pxa25x())
+                ret = cpufreq_register_driver(&pxa_cpufreq_driver);
+        return ret;
+}
+
+static void __exit pxa_cpu_exit(void)
+{
+        if (cpu_is_pxa25x())
+                cpufreq_unregister_driver(&pxa_cpufreq_driver);
+}
+
+
+MODULE_AUTHOR ("Intrinsyc Software Inc.");
+MODULE_DESCRIPTION ("CPU frequency changing driver for the PXA architecture");
+MODULE_LICENSE("GPL");
+module_init(pxa_cpu_init);
+module_exit(pxa_cpu_exit);