[ARM] pxa: add vcc_core regulation for cpufreq on pxa2xx

Add voltage regulation capability to pxa2xx cpufreq
driver. The cpufreq will ask for a "vcc_core" regulator to
the regulator framework.

If a regulator is found at probe time, it will be used with
values specified in PXA270 Electrical, Mechanical, and
Thermal Specifications.

If not, it will be assumed for now that frequency change
will work without voltage control. This assumes that the
IPL/SPL installs sane values to an existing voltage
regulator (ie. voltage high enough to support the full
range).

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Eric Miao <eric.miao@marvell.com>

arch/arm/mach-pxa/cpufreq-pxa2xx.c

@@ -36,6 +36,8 @@
 #include <linux/sched.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
+#include <linux/err.h>
+#include <linux/regulator/consumer.h>
 
 #include <mach/pxa2xx-regs.h>
 
@@ -47,6 +49,8 @@ MODULE_PARM_DESC(freq_debug, "Set the debug messages to on=1/off=0");
 #define freq_debug  0
 #endif
 
+static struct regulator *vcc_core;
+
 static unsigned int pxa27x_maxfreq;
 module_param(pxa27x_maxfreq, uint, 0);
 MODULE_PARM_DESC(pxa27x_maxfreq, "Set the pxa27x maxfreq in MHz"
@@ -58,6 +62,8 @@ typedef struct {
 	unsigned int cccr;
 	unsigned int div2;
 	unsigned int cclkcfg;
+	int vmin;
+	int vmax;
 } pxa_freqs_t;
 
 /* Define the refresh period in mSec for the SDRAM and the number of rows */
@@ -82,24 +88,24 @@ static unsigned int sdram_rows;
 
 static pxa_freqs_t pxa255_run_freqs[] =
 {
-	/* CPU   MEMBUS  CCCR  DIV2 CCLKCFG	   run  turbo PXbus SDRAM */
-	{ 99500,  99500, 0x121, 1,  CCLKCFG},	/*  99,   99,   50,   50  */
-	{132700, 132700, 0x123, 1,  CCLKCFG},	/* 133,  133,   66,   66  */
-	{199100,  99500, 0x141, 0,  CCLKCFG},	/* 199,  199,   99,   99  */
-	{265400, 132700, 0x143, 1,  CCLKCFG},	/* 265,  265,  133,   66  */
-	{331800, 165900, 0x145, 1,  CCLKCFG},	/* 331,  331,  166,   83  */
-	{398100,  99500, 0x161, 0,  CCLKCFG},	/* 398,  398,  196,   99  */
+	/* CPU   MEMBUS  CCCR  DIV2 CCLKCFG	           run  turbo PXbus SDRAM */
+	{ 99500,  99500, 0x121, 1,  CCLKCFG, -1, -1},	/*  99,   99,   50,   50  */
+	{132700, 132700, 0x123, 1,  CCLKCFG, -1, -1},	/* 133,  133,   66,   66  */
+	{199100,  99500, 0x141, 0,  CCLKCFG, -1, -1},	/* 199,  199,   99,   99  */
+	{265400, 132700, 0x143, 1,  CCLKCFG, -1, -1},	/* 265,  265,  133,   66  */
+	{331800, 165900, 0x145, 1,  CCLKCFG, -1, -1},	/* 331,  331,  166,   83  */
+	{398100,  99500, 0x161, 0,  CCLKCFG, -1, -1},	/* 398,  398,  196,   99  */
 };
 
 /* Use the turbo mode frequencies for the CPUFREQ_POLICY_POWERSAVE policy */
 static pxa_freqs_t pxa255_turbo_freqs[] =
 {
 	/* CPU   MEMBUS  CCCR  DIV2 CCLKCFG	   run  turbo PXbus SDRAM */
-	{ 99500, 99500,  0x121, 1,  CCLKCFG},	/*  99,   99,   50,   50  */
-	{199100, 99500,  0x221, 0,  CCLKCFG},	/*  99,  199,   50,   99  */
-	{298500, 99500,  0x321, 0,  CCLKCFG},	/*  99,  287,   50,   99  */
-	{298600, 99500,  0x1c1, 0,  CCLKCFG},	/* 199,  287,   99,   99  */
-	{398100, 99500,  0x241, 0,  CCLKCFG},	/* 199,  398,   99,   99  */
+	{ 99500, 99500,  0x121, 1,  CCLKCFG, -1, -1},	/*  99,   99,   50,   50  */
+	{199100, 99500,  0x221, 0,  CCLKCFG, -1, -1},	/*  99,  199,   50,   99  */
+	{298500, 99500,  0x321, 0,  CCLKCFG, -1, -1},	/*  99,  287,   50,   99  */
+	{298600, 99500,  0x1c1, 0,  CCLKCFG, -1, -1},	/* 199,  287,   99,   99  */
+	{398100, 99500,  0x241, 0,  CCLKCFG, -1, -1},	/* 199,  398,   99,   99  */
 };
 
 #define NUM_PXA25x_RUN_FREQS ARRAY_SIZE(pxa255_run_freqs)
@@ -148,13 +154,13 @@ MODULE_PARM_DESC(pxa255_turbo_table, "Selects the frequency table (0 = run table
    ((T)  ? CCLKCFG_TURBO : 0))
 
 static pxa_freqs_t pxa27x_freqs[] = {
-	{104000, 104000, PXA27x_CCCR(1,	 8, 2), 0, CCLKCFG2(1, 0, 1)},
-	{156000, 104000, PXA27x_CCCR(1,	 8, 6), 0, CCLKCFG2(1, 1, 1)},
-	{208000, 208000, PXA27x_CCCR(0, 16, 2), 1, CCLKCFG2(0, 0, 1)},
-	{312000, 208000, PXA27x_CCCR(1, 16, 3), 1, CCLKCFG2(1, 0, 1)},
-	{416000, 208000, PXA27x_CCCR(1, 16, 4), 1, CCLKCFG2(1, 0, 1)},
-	{520000, 208000, PXA27x_CCCR(1, 16, 5), 1, CCLKCFG2(1, 0, 1)},
-	{624000, 208000, PXA27x_CCCR(1, 16, 6), 1, CCLKCFG2(1, 0, 1)}
+	{104000, 104000, PXA27x_CCCR(1,	 8, 2), 0, CCLKCFG2(1, 0, 1),  900000, 1705000 },
+	{156000, 104000, PXA27x_CCCR(1,	 8, 6), 0, CCLKCFG2(1, 1, 1), 1000000, 1705000 },
+	{208000, 208000, PXA27x_CCCR(0, 16, 2), 1, CCLKCFG2(0, 0, 1), 1180000, 1705000 },
+	{312000, 208000, PXA27x_CCCR(1, 16, 3), 1, CCLKCFG2(1, 0, 1), 1250000, 1705000 },
+	{416000, 208000, PXA27x_CCCR(1, 16, 4), 1, CCLKCFG2(1, 0, 1), 1350000, 1705000 },
+	{520000, 208000, PXA27x_CCCR(1, 16, 5), 1, CCLKCFG2(1, 0, 1), 1450000, 1705000 },
+	{624000, 208000, PXA27x_CCCR(1, 16, 6), 1, CCLKCFG2(1, 0, 1), 1550000, 1705000 }
 };
 
 #define NUM_PXA27x_FREQS ARRAY_SIZE(pxa27x_freqs)
@@ -163,6 +169,47 @@ static struct cpufreq_frequency_table
 
 extern unsigned get_clk_frequency_khz(int info);
 
+#ifdef CONFIG_REGULATOR
+
+static int pxa_cpufreq_change_voltage(pxa_freqs_t *pxa_freq)
+{
+	int ret = 0;
+	int vmin, vmax;
+
+	if (!cpu_is_pxa27x())
+		return 0;
+
+	vmin = pxa_freq->vmin;
+	vmax = pxa_freq->vmax;
+	if ((vmin == -1) || (vmax == -1))
+		return 0;
+
+	ret = regulator_set_voltage(vcc_core, vmin, vmax);
+	if (ret)
+		pr_err("cpufreq: Failed to set vcc_core in [%dmV..%dmV]\n",
+		       vmin, vmax);
+	return ret;
+}
+
+static __init void pxa_cpufreq_init_voltages(void)
+{
+	vcc_core = regulator_get(NULL, "vcc_core");
+	if (IS_ERR(vcc_core)) {
+		pr_info("cpufreq: Didn't find vcc_core regulator\n");
+		vcc_core = NULL;
+	} else {
+		pr_info("cpufreq: Found vcc_core regulator\n");
+	}
+}
+#else
+static int pxa_cpufreq_change_voltage(pxa_freqs_t *pxa_freq)
+{
+	return 0;
+}
+
+static __init void pxa_cpufreq_init_voltages(void) { }
+#endif
+
 static void find_freq_tables(struct cpufreq_frequency_table **freq_table,
 			     pxa_freqs_t **pxa_freqs)
 {
@@ -251,6 +298,7 @@ static int pxa_set_target(struct cpufreq_policy *policy,
 	unsigned long flags;
 	unsigned int new_freq_cpu, new_freq_mem;
 	unsigned int unused, preset_mdrefr, postset_mdrefr, cclkcfg;
+	int ret = 0;
 
 	/* Get the current policy */
 	find_freq_tables(&pxa_freqs_table, &pxa_freq_settings);
@@ -273,6 +321,10 @@ static int pxa_set_target(struct cpufreq_policy *policy,
 			 freqs.new / 1000, (pxa_freq_settings[idx].div2) ?
 			 (new_freq_mem / 2000) : (new_freq_mem / 1000));
 
+	if (vcc_core && freqs.new > freqs.old)
+		ret = pxa_cpufreq_change_voltage(&pxa_freq_settings[idx]);
+	if (ret)
+		return ret;
 	/*
 	 * Tell everyone what we're about to do...
 	 * you should add a notify client with any platform specific
@@ -335,6 +387,18 @@ static int pxa_set_target(struct cpufreq_policy *policy,
 	 */
 	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 
+	/*
+	 * Even if voltage setting fails, we don't report it, as the frequency
+	 * change succeeded. The voltage reduction is not a critical failure,
+	 * only power savings will suffer from this.
+	 *
+	 * Note: if the voltage change fails, and a return value is returned, a
+	 * bug is triggered (seems a deadlock). Should anybody find out where,
+	 * the "return 0" should become a "return ret".
+	 */
+	if (vcc_core && freqs.new < freqs.old)
+		ret = pxa_cpufreq_change_voltage(&pxa_freq_settings[idx]);
+
 	return 0;
 }
 
@@ -349,6 +413,8 @@ static __init int pxa_cpufreq_init(struct cpufreq_policy *policy)
 	if (cpu_is_pxa27x())
 		pxa27x_guess_max_freq();
 
+	pxa_cpufreq_init_voltages();
+
 	init_sdram_rows();
 
 	/* set default policy and cpuinfo */