[CPUFREQ] AMD Elan SC520 cpufreq driver.

From: Sean Young <sean@mess.org>
Signed-off-by: Dave Jones <davej@redhat.com>

3 files changed, 200 insertions, 1 deletions

diff --git a/arch/i386/kernel/cpu/cpufreq/Kconfig b/arch/i386/kernel/cpu/cpufreq/Kconfig
index f25ffd74235c..0f1eb507233b 100644
--- a/arch/i386/kernel/cpu/cpufreq/Kconfig
+++ b/arch/i386/kernel/cpu/cpufreq/Kconfig
@@ -23,7 +23,7 @@ config X86_ACPI_CPUFREQ
           If in doubt, say N.
 
 config ELAN_CPUFREQ
-        tristate "AMD Elan"
+        tristate "AMD Elan SC400 and SC410"
         select CPU_FREQ_TABLE
         depends on X86_ELAN
         ---help---
@@ -38,6 +38,18 @@ config ELAN_CPUFREQ
 
           If in doubt, say N.
 
+config SC520_CPUFREQ
+        tristate "AMD Elan SC520"
+        select CPU_FREQ_TABLE
+        depends on X86_ELAN
+        ---help---
+          This adds the CPUFreq driver for AMD Elan SC520 processor.
+
+          For details, take a look at <file:Documentation/cpu-freq/>.
+
+          If in doubt, say N.
+
+
 config X86_POWERNOW_K6
         tristate "AMD Mobile K6-2/K6-3 PowerNow!"
         select CPU_FREQ_TABLE
diff --git a/arch/i386/kernel/cpu/cpufreq/Makefile b/arch/i386/kernel/cpu/cpufreq/Makefile
index a922e97aeedd..2e894f1c8910 100644
--- a/arch/i386/kernel/cpu/cpufreq/Makefile
+++ b/arch/i386/kernel/cpu/cpufreq/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_X86_POWERNOW_K7)		+= powernow-k7.o
 obj-$(CONFIG_X86_POWERNOW_K8)           += powernow-k8.o
 obj-$(CONFIG_X86_LONGHAUL)              += longhaul.o
 obj-$(CONFIG_ELAN_CPUFREQ)              += elanfreq.o
+obj-$(CONFIG_SC520_CPUFREQ)             += sc520_freq.o
 obj-$(CONFIG_X86_LONGRUN)               += longrun.o  
 obj-$(CONFIG_X86_GX_SUSPMOD)            += gx-suspmod.o
 obj-$(CONFIG_X86_SPEEDSTEP_ICH)         += speedstep-ich.o
diff --git a/arch/i386/kernel/cpu/cpufreq/sc520_freq.c b/arch/i386/kernel/cpu/cpufreq/sc520_freq.c
new file mode 100644
index 000000000000..ef457d50f4ac
--- /dev/null
+++ b/arch/i386/kernel/cpu/cpufreq/sc520_freq.c
@@ -0,0 +1,186 @@
+/*
+ *      sc520_freq.c: cpufreq driver for the AMD Elan sc520
+ *
+ *      Copyright (C) 2005 Sean Young <sean@mess.org>
+ *
+ *      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.
+ *
+ *      Based on elanfreq.c
+ *
+ *      2005-03-30: - initial revision
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+#include <linux/delay.h>
+#include <linux/cpufreq.h>
+
+#include <asm/msr.h>
+#include <asm/timex.h>
+#include <asm/io.h>
+
+#define MMCR_BASE       0xfffef000      /* The default base address */
+#define OFFS_CPUCTL     0x2   /* CPU Control Register */
+
+static __u8 __iomem *cpuctl;
+
+#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "sc520_freq", msg)
+
+static struct cpufreq_frequency_table sc520_freq_table[] = {
+        {0x01,  100000},
+        {0x02,  133000},
+        {0,     CPUFREQ_TABLE_END},
+};
+
+static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu)
+{
+        u8 clockspeed_reg = *cpuctl;
+
+        switch (clockspeed_reg & 0x03) {
+        default:
+                printk(KERN_ERR "sc520_freq: error: cpuctl register has unexpected value %02x\n", clockspeed_reg);
+        case 0x01:
+                return 100000;
+        case 0x02:
+                return 133000;
+        }
+}
+
+static void sc520_freq_set_cpu_state (unsigned int state)
+{
+
+        struct cpufreq_freqs    freqs;
+        u8 clockspeed_reg;
+
+        freqs.old = sc520_freq_get_cpu_frequency(0);
+        freqs.new = sc520_freq_table[state].frequency;
+        freqs.cpu = 0; /* AMD Elan is UP */
+
+        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+        dprintk("attempting to set frequency to %i kHz\n",
+                        sc520_freq_table[state].frequency);
+
+        local_irq_disable();
+
+        clockspeed_reg = *cpuctl & ~0x03;
+        *cpuctl = clockspeed_reg | sc520_freq_table[state].index;
+
+        local_irq_enable();
+
+        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+};
+
+static int sc520_freq_verify (struct cpufreq_policy *policy)
+{
+        return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]);
+}
+
+static int sc520_freq_target (struct cpufreq_policy *policy,
+                            unsigned int target_freq,
+                            unsigned int relation)
+{
+        unsigned int newstate = 0;
+
+        if (cpufreq_frequency_table_target(policy, sc520_freq_table, target_freq, relation, &newstate))
+                return -EINVAL;
+
+        sc520_freq_set_cpu_state(newstate);
+
+        return 0;
+}
+
+
+/*
+ *      Module init and exit code
+ */
+
+static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
+{
+        struct cpuinfo_x86 *c = cpu_data;
+        int result;
+
+        /* capability check */
+        if (c->x86_vendor != X86_VENDOR_AMD ||
+            c->x86 != 4 || c->x86_model != 9)
+                return -ENODEV;
+
+        /* cpuinfo and default policy values */
+        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+        policy->cpuinfo.transition_latency = 1000000; /* 1ms */
+        policy->cur = sc520_freq_get_cpu_frequency(0);
+
+        result = cpufreq_frequency_table_cpuinfo(policy, sc520_freq_table);
+        if (result)
+                return (result);
+
+        cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu);
+
+        return 0;
+}
+
+
+static int sc520_freq_cpu_exit(struct cpufreq_policy *policy)
+{
+        cpufreq_frequency_table_put_attr(policy->cpu);
+        return 0;
+}
+
+
+static struct freq_attr* sc520_freq_attr[] = {
+        &cpufreq_freq_attr_scaling_available_freqs,
+        NULL,
+};
+
+
+static struct cpufreq_driver sc520_freq_driver = {
+        .get    = sc520_freq_get_cpu_frequency,
+        .verify = sc520_freq_verify,
+        .target = sc520_freq_target,
+        .init   = sc520_freq_cpu_init,
+        .exit   = sc520_freq_cpu_exit,
+        .name   = "sc520_freq",
+        .owner  = THIS_MODULE,
+        .attr   = sc520_freq_attr,
+};
+
+
+static int __init sc520_freq_init(void)
+{
+        struct cpuinfo_x86 *c = cpu_data;
+
+        /* Test if we have the right hardware */
+        if(c->x86_vendor != X86_VENDOR_AMD ||
+                                c->x86 != 4 || c->x86_model != 9) {
+                dprintk("no Elan SC520 processor found!\n");
+                return -ENODEV;
+        }
+        cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
+        if(!cpuctl) {
+                printk(KERN_ERR "sc520_freq: error: failed to remap memory\n");
+                return -ENOMEM;
+        }
+
+        return cpufreq_register_driver(&sc520_freq_driver);
+}
+
+
+static void __exit sc520_freq_exit(void)
+{
+        cpufreq_unregister_driver(&sc520_freq_driver);
+        iounmap(cpuctl);
+}
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sean Young <sean@mess.org>");
+MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU");
+
+module_init(sc520_freq_init);
+module_exit(sc520_freq_exit);
+