[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>

4 files changed, 325 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pasemi/Makefile b/arch/powerpc/platforms/pasemi/Makefile
index 7ffd43b43e02..2cd2a4f26a48 100644
--- a/arch/powerpc/platforms/pasemi/Makefile
+++ b/arch/powerpc/platforms/pasemi/Makefile
@@ -1,2 +1,3 @@
 obj-y   += setup.o pci.o time.o idle.o powersave.o iommu.o
 obj-$(CONFIG_PPC_PASEMI_MDIO)   += gpio_mdio.o
+obj-$(CONFIG_PPC_PASEMI_CPUFREQ) += cpufreq.o
diff --git a/arch/powerpc/platforms/pasemi/cpufreq.c b/arch/powerpc/platforms/pasemi/cpufreq.c
new file mode 100644
index 000000000000..4dd5c512f869
--- /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>");
diff --git a/arch/powerpc/platforms/pasemi/idle.c b/arch/powerpc/platforms/pasemi/idle.c
index 1ca3ff381591..5985ce0c5c48 100644
--- a/arch/powerpc/platforms/pasemi/idle.c
+++ b/arch/powerpc/platforms/pasemi/idle.c
@@ -61,6 +61,10 @@ static int pasemi_system_reset_exception(struct pt_regs *regs)
                 /* do system reset */
                 return 0;
         }
+
+        /* Set higher astate since we come out of power savings at 0 */
+        restore_astate(hard_smp_processor_id());
+
         /* everything handled */
         regs->msr |= MSR_RI;
         return 1;
@@ -68,6 +72,11 @@ static int pasemi_system_reset_exception(struct pt_regs *regs)
 
 void __init pasemi_idle_init(void)
 {
+#ifndef CONFIG_PPC_PASEMI_CPUFREQ
+        printk(KERN_WARNING "No cpufreq driver, powersavings modes disabled\n");
+        current_mode = 0;
+#endif
+
         ppc_md.system_reset_exception = pasemi_system_reset_exception;
         ppc_md.power_save = modes[current_mode].entry;
         printk(KERN_INFO "Using PA6T idle loop (%s)\n", modes[current_mode].name);
diff --git a/arch/powerpc/platforms/pasemi/pasemi.h b/arch/powerpc/platforms/pasemi/pasemi.h
index 2d3927e6edb0..be8495497611 100644
--- a/arch/powerpc/platforms/pasemi/pasemi.h
+++ b/arch/powerpc/platforms/pasemi/pasemi.h
@@ -14,6 +14,14 @@ extern void __init pasemi_idle_init(void);
 extern void idle_spin(void);
 extern void idle_doze(void);
 
+/* Restore astate to last set */
+#ifdef CONFIG_PPC_PASEMI_CPUFREQ
+extern void restore_astate(int cpu);
+#else
+static inline void restore_astate(int cpu)
+{
+}
+#endif
 
 
 #endif /* _PASEMI_PASEMI_H */