[POWERPC] pasemi: Cpufreq driver

Cpufreq driver for PA Semi PWRficient processors.

Signed-off-by: Egor Martovetsky <egor@pasemi.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 307 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pasemi/cpufreq.c b/arch/powerpc/platforms/pasemi/cpufreq.c
new file mode 100644
index 00000000000..4dd5c512f86
--- /dev/null
+++ b/arch/powerpc/platforms/pasemi/cpufreq.c
@@ -0,0 +1,307 @@
+/*
+ * Copyright (C) 2007 PA Semi, Inc
+ *
+ * Authors: Egor Martovetsky <egor@pasemi.com>
+ *	    Olof Johansson <olof@lixom.net>
+ *
+ * Maintained by: Olof Johansson <olof@lixom.net>
+ *
+ * Based on arch/powerpc/platforms/cell/cbe_cpufreq.c:
+ * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
+ *
+ * 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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/cpufreq.h>
+#include <linux/timer.h>
+
+#include <asm/hw_irq.h>
+#include <asm/io.h>
+#include <asm/prom.h>
+
+#define SDCASR_REG		0x0100
+#define SDCASR_REG_STRIDE	0x1000
+#define SDCPWR_CFGA0_REG	0x0100
+#define SDCPWR_PWST0_REG	0x0000
+#define SDCPWR_GIZTIME_REG	0x0440
+
+/* SDCPWR_GIZTIME_REG fields */
+#define SDCPWR_GIZTIME_GR	0x80000000
+#define SDCPWR_GIZTIME_LONGLOCK	0x000000ff
+
+/* Offset of ASR registers from SDC base */
+#define SDCASR_OFFSET		0x120000
+
+static void __iomem *sdcpwr_mapbase;
+static void __iomem *sdcasr_mapbase;
+
+static DEFINE_MUTEX(pas_switch_mutex);
+
+/* Current astate, is used when waking up from power savings on
+ * one core, in case the other core has switched states during
+ * the idle time.
+ */
+static int current_astate;
+
+/* We support 5(A0-A4) power states excluding turbo(A5-A6) modes */
+static struct cpufreq_frequency_table pas_freqs[] = {
+	{0,	0},
+	{1,	0},
+	{2,	0},
+	{3,	0},
+	{4,	0},
+	{0,	CPUFREQ_TABLE_END},
+};
+
+static struct freq_attr *pas_cpu_freqs_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
+
+/*
+ * hardware specific functions
+ */
+
+static int get_astate_freq(int astate)
+{
+	u32 ret;
+	ret = in_le32(sdcpwr_mapbase + SDCPWR_CFGA0_REG + (astate * 0x10));
+
+	return ret & 0x3f;
+}
+
+static int get_cur_astate(int cpu)
+{
+	u32 ret;
+
+	ret = in_le32(sdcpwr_mapbase + SDCPWR_PWST0_REG);
+	ret = (ret >> (cpu * 4)) & 0x7;
+
+	return ret;
+}
+
+static int get_gizmo_latency(void)
+{
+	u32 giztime, ret;
+
+	giztime = in_le32(sdcpwr_mapbase + SDCPWR_GIZTIME_REG);
+
+	/* just provide the upper bound */
+	if (giztime & SDCPWR_GIZTIME_GR)
+		ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 128000;
+	else
+		ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 1000;
+
+	return ret;
+}
+
+static void set_astate(int cpu, unsigned int astate)
+{
+	u64 flags;
+
+	/* Return if called before init has run */
+	if (unlikely(!sdcasr_mapbase))
+		return;
+
+	local_irq_save(flags);
+
+	out_le32(sdcasr_mapbase + SDCASR_REG + SDCASR_REG_STRIDE*cpu, astate);
+
+	local_irq_restore(flags);
+}
+
+void restore_astate(int cpu)
+{
+	set_astate(cpu, current_astate);
+}
+
+/*
+ * cpufreq functions
+ */
+
+static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+	u32 *max_freq;
+	int i, cur_astate;
+	struct resource res;
+	struct device_node *cpu, *dn;
+	int err = -ENODEV;
+
+	cpu = of_get_cpu_node(policy->cpu, NULL);
+
+	if (!cpu)
+		goto out;
+
+	dn = of_find_compatible_node(NULL, "sdc", "1682m-sdc");
+	if (!dn)
+		goto out;
+	err = of_address_to_resource(dn, 0, &res);
+	of_node_put(dn);
+	if (err)
+		goto out;
+	sdcasr_mapbase = ioremap(res.start + SDCASR_OFFSET, 0x2000);
+	if (!sdcasr_mapbase) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	dn = of_find_compatible_node(NULL, "gizmo", "1682m-gizmo");
+	if (!dn) {
+		err = -ENODEV;
+		goto out_unmap_sdcasr;
+	}
+	err = of_address_to_resource(dn, 0, &res);
+	of_node_put(dn);
+	if (err)
+		goto out_unmap_sdcasr;
+	sdcpwr_mapbase = ioremap(res.start, 0x1000);
+	if (!sdcpwr_mapbase) {
+		err = -EINVAL;
+		goto out_unmap_sdcasr;
+	}
+
+	pr_debug("init cpufreq on CPU %d\n", policy->cpu);
+
+	max_freq = (u32*) get_property(cpu, "clock-frequency", NULL);
+	if (!max_freq) {
+		err = -EINVAL;
+		goto out_unmap_sdcpwr;
+	}
+
+	/* we need the freq in kHz */
+	*max_freq /= 1000;
+
+	pr_debug("max clock-frequency is at %u kHz\n", *max_freq);
+	pr_debug("initializing frequency table\n");
+
+	/* initialize frequency table */
+	for (i=0; pas_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
+		pas_freqs[i].frequency = get_astate_freq(pas_freqs[i].index) * 100000;
+		pr_debug("%d: %d\n", i, pas_freqs[i].frequency);
+	}
+
+	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+
+	policy->cpuinfo.transition_latency = get_gizmo_latency();
+
+	cur_astate = get_cur_astate(policy->cpu);
+	pr_debug("current astate is at %d\n",cur_astate);
+
+	policy->cur = pas_freqs[cur_astate].frequency;
+	policy->cpus = cpu_online_map;
+
+	cpufreq_frequency_table_get_attr(pas_freqs, policy->cpu);
+
+	/* this ensures that policy->cpuinfo_min and policy->cpuinfo_max
+	 * are set correctly
+	 */
+	return cpufreq_frequency_table_cpuinfo(policy, pas_freqs);
+
+out_unmap_sdcpwr:
+	iounmap(sdcpwr_mapbase);
+
+out_unmap_sdcasr:
+	iounmap(sdcasr_mapbase);
+out:
+	return err;
+}
+
+static int pas_cpufreq_cpu_exit(struct cpufreq_policy *policy)
+{
+	if (sdcasr_mapbase)
+		iounmap(sdcasr_mapbase);
+	if (sdcpwr_mapbase)
+		iounmap(sdcpwr_mapbase);
+
+	cpufreq_frequency_table_put_attr(policy->cpu);
+	return 0;
+}
+
+static int pas_cpufreq_verify(struct cpufreq_policy *policy)
+{
+	return cpufreq_frequency_table_verify(policy, pas_freqs);
+}
+
+static int pas_cpufreq_target(struct cpufreq_policy *policy,
+			      unsigned int target_freq,
+			      unsigned int relation)
+{
+	struct cpufreq_freqs freqs;
+	int pas_astate_new;
+	int i;
+
+	cpufreq_frequency_table_target(policy,
+				       pas_freqs,
+				       target_freq,
+				       relation,
+				       &pas_astate_new);
+
+	freqs.old = policy->cur;
+	freqs.new = pas_freqs[pas_astate_new].frequency;
+	freqs.cpu = policy->cpu;
+
+	mutex_lock(&pas_switch_mutex);
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+	pr_debug("setting frequency for cpu %d to %d kHz, 1/%d of max frequency\n",
+		 policy->cpu,
+		 pas_freqs[pas_astate_new].frequency,
+		 pas_freqs[pas_astate_new].index);
+
+	current_astate = pas_astate_new;
+
+	for_each_online_cpu(i)
+		set_astate(i, pas_astate_new);
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+	mutex_unlock(&pas_switch_mutex);
+
+	return 0;
+}
+
+static struct cpufreq_driver pas_cpufreq_driver = {
+	.name		= "pas-cpufreq",
+	.owner		= THIS_MODULE,
+	.flags		= CPUFREQ_CONST_LOOPS,
+	.init		= pas_cpufreq_cpu_init,
+	.exit		= pas_cpufreq_cpu_exit,
+	.verify		= pas_cpufreq_verify,
+	.target		= pas_cpufreq_target,
+	.attr		= pas_cpu_freqs_attr,
+};
+
+/*
+ * module init and destoy
+ */
+
+static int __init pas_cpufreq_init(void)
+{
+	if (!machine_is_compatible("PA6T-1682M"))
+		return -ENODEV;
+
+	return cpufreq_register_driver(&pas_cpufreq_driver);
+}
+
+static void __exit pas_cpufreq_exit(void)
+{
+	cpufreq_unregister_driver(&pas_cpufreq_driver);
+}
+
+module_init(pas_cpufreq_init);
+module_exit(pas_cpufreq_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>, Olof Johansson <olof@lixom.net>");