[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>

1 files changed, 293 insertions, 0 deletions

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);