powerpc/cpufreq: Add cpufreq driver for Momentum Maple boards
Add simple cpufreq driver for Maple-based boards (ppc970fx evaluation
kit and others). Driver is based on a cpufreq driver for 64-bit powermac
boxes with all pmac-dependant features removed and simple cleanup
applied.
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/drivers/cpufreq/maple-cpufreq.c b/drivers/cpufreq/maple-cpufreq.c
new file mode 100644
index 0000000..89b178a3
--- /dev/null
+++ b/drivers/cpufreq/maple-cpufreq.c
@@ -0,0 +1,309 @@
+/*
+ * Copyright (C) 2011 Dmitry Eremin-Solenikov
+ * Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
+ * and Markus Demleitner <msdemlei@cl.uni-heidelberg.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This driver adds basic cpufreq support for SMU & 970FX based G5 Macs,
+ * that is iMac G5 and latest single CPU desktop.
+ */
+
+#undef DEBUG
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/time.h>
+#include <linux/of.h>
+
+#define DBG(fmt...) pr_debug(fmt)
+
+/* see 970FX user manual */
+
+#define SCOM_PCR 0x0aa001 /* PCR scom addr */
+
+#define PCR_HILO_SELECT 0x80000000U /* 1 = PCR, 0 = PCRH */
+#define PCR_SPEED_FULL 0x00000000U /* 1:1 speed value */
+#define PCR_SPEED_HALF 0x00020000U /* 1:2 speed value */
+#define PCR_SPEED_QUARTER 0x00040000U /* 1:4 speed value */
+#define PCR_SPEED_MASK 0x000e0000U /* speed mask */
+#define PCR_SPEED_SHIFT 17
+#define PCR_FREQ_REQ_VALID 0x00010000U /* freq request valid */
+#define PCR_VOLT_REQ_VALID 0x00008000U /* volt request valid */
+#define PCR_TARGET_TIME_MASK 0x00006000U /* target time */
+#define PCR_STATLAT_MASK 0x00001f00U /* STATLAT value */
+#define PCR_SNOOPLAT_MASK 0x000000f0U /* SNOOPLAT value */
+#define PCR_SNOOPACC_MASK 0x0000000fU /* SNOOPACC value */
+
+#define SCOM_PSR 0x408001 /* PSR scom addr */
+/* warning: PSR is a 64 bits register */
+#define PSR_CMD_RECEIVED 0x2000000000000000U /* command received */
+#define PSR_CMD_COMPLETED 0x1000000000000000U /* command completed */
+#define PSR_CUR_SPEED_MASK 0x0300000000000000U /* current speed */
+#define PSR_CUR_SPEED_SHIFT (56)
+
+/*
+ * The G5 only supports two frequencies (Quarter speed is not supported)
+ */
+#define CPUFREQ_HIGH 0
+#define CPUFREQ_LOW 1
+
+static struct cpufreq_frequency_table maple_cpu_freqs[] = {
+ {CPUFREQ_HIGH, 0},
+ {CPUFREQ_LOW, 0},
+ {0, CPUFREQ_TABLE_END},
+};
+
+static struct freq_attr *maple_cpu_freqs_attr[] = {
+ &cpufreq_freq_attr_scaling_available_freqs,
+ NULL,
+};
+
+/* Power mode data is an array of the 32 bits PCR values to use for
+ * the various frequencies, retrieved from the device-tree
+ */
+static int maple_pmode_cur;
+
+static DEFINE_MUTEX(maple_switch_mutex);
+
+static const u32 *maple_pmode_data;
+static int maple_pmode_max;
+
+/*
+ * SCOM based frequency switching for 970FX rev3
+ */
+static int maple_scom_switch_freq(int speed_mode)
+{
+ unsigned long flags;
+ int to;
+
+ local_irq_save(flags);
+
+ /* Clear PCR high */
+ scom970_write(SCOM_PCR, 0);
+ /* Clear PCR low */
+ scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0);
+ /* Set PCR low */
+ scom970_write(SCOM_PCR, PCR_HILO_SELECT |
+ maple_pmode_data[speed_mode]);
+
+ /* Wait for completion */
+ for (to = 0; to < 10; to++) {
+ unsigned long psr = scom970_read(SCOM_PSR);
+
+ if ((psr & PSR_CMD_RECEIVED) == 0 &&
+ (((psr >> PSR_CUR_SPEED_SHIFT) ^
+ (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3)
+ == 0)
+ break;
+ if (psr & PSR_CMD_COMPLETED)
+ break;
+ udelay(100);
+ }
+
+ local_irq_restore(flags);
+
+ maple_pmode_cur = speed_mode;
+ ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul;
+
+ return 0;
+}
+
+static int maple_scom_query_freq(void)
+{
+ unsigned long psr = scom970_read(SCOM_PSR);
+ int i;
+
+ for (i = 0; i <= maple_pmode_max; i++)
+ if ((((psr >> PSR_CUR_SPEED_SHIFT) ^
+ (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0)
+ break;
+ return i;
+}
+
+/*
+ * Common interface to the cpufreq core
+ */
+
+static int maple_cpufreq_verify(struct cpufreq_policy *policy)
+{
+ return cpufreq_frequency_table_verify(policy, maple_cpu_freqs);
+}
+
+static int maple_cpufreq_target(struct cpufreq_policy *policy,
+ unsigned int target_freq, unsigned int relation)
+{
+ unsigned int newstate = 0;
+ struct cpufreq_freqs freqs;
+ int rc;
+
+ if (cpufreq_frequency_table_target(policy, maple_cpu_freqs,
+ target_freq, relation, &newstate))
+ return -EINVAL;
+
+ if (maple_pmode_cur == newstate)
+ return 0;
+
+ mutex_lock(&maple_switch_mutex);
+
+ freqs.old = maple_cpu_freqs[maple_pmode_cur].frequency;
+ freqs.new = maple_cpu_freqs[newstate].frequency;
+ freqs.cpu = 0;
+
+ cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+ rc = maple_scom_switch_freq(newstate);
+ cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+ mutex_unlock(&maple_switch_mutex);
+
+ return rc;
+}
+
+static unsigned int maple_cpufreq_get_speed(unsigned int cpu)
+{
+ return maple_cpu_freqs[maple_pmode_cur].frequency;
+}
+
+static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+ policy->cpuinfo.transition_latency = 12000;
+ policy->cur = maple_cpu_freqs[maple_scom_query_freq()].frequency;
+ /* secondary CPUs are tied to the primary one by the
+ * cpufreq core if in the secondary policy we tell it that
+ * it actually must be one policy together with all others. */
+ cpumask_copy(policy->cpus, cpu_online_mask);
+ cpufreq_frequency_table_get_attr(maple_cpu_freqs, policy->cpu);
+
+ return cpufreq_frequency_table_cpuinfo(policy,
+ maple_cpu_freqs);
+}
+
+
+static struct cpufreq_driver maple_cpufreq_driver = {
+ .name = "maple",
+ .owner = THIS_MODULE,
+ .flags = CPUFREQ_CONST_LOOPS,
+ .init = maple_cpufreq_cpu_init,
+ .verify = maple_cpufreq_verify,
+ .target = maple_cpufreq_target,
+ .get = maple_cpufreq_get_speed,
+ .attr = maple_cpu_freqs_attr,
+};
+
+static int __init maple_cpufreq_init(void)
+{
+ struct device_node *cpus;
+ struct device_node *cpunode;
+ unsigned int psize;
+ unsigned long max_freq;
+ const u32 *valp;
+ u32 pvr_hi;
+ int rc = -ENODEV;
+
+ /*
+ * Behave here like powermac driver which checks machine compatibility
+ * to ease merging of two drivers in future.
+ */
+ if (!of_machine_is_compatible("Momentum,Maple") &&
+ !of_machine_is_compatible("Momentum,Apache"))
+ return 0;
+
+ cpus = of_find_node_by_path("/cpus");
+ if (cpus == NULL) {
+ DBG("No /cpus node !\n");
+ return -ENODEV;
+ }
+
+ /* Get first CPU node */
+ for (cpunode = NULL;
+ (cpunode = of_get_next_child(cpus, cpunode)) != NULL;) {
+ const u32 *reg = of_get_property(cpunode, "reg", NULL);
+ if (reg == NULL || (*reg) != 0)
+ continue;
+ if (!strcmp(cpunode->type, "cpu"))
+ break;
+ }
+ if (cpunode == NULL) {
+ printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n");
+ goto bail_cpus;
+ }
+
+ /* Check 970FX for now */
+ /* we actually don't care on which CPU to access PVR */
+ pvr_hi = PVR_VER(mfspr(SPRN_PVR));
+ if (pvr_hi != 0x3c && pvr_hi != 0x44) {
+ printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n",
+ pvr_hi);
+ goto bail_noprops;
+ }
+
+ /* Look for the powertune data in the device-tree */
+ /*
+ * On Maple this property is provided by PIBS in dual-processor config,
+ * not provided by PIBS in CPU0 config and also not provided by SLOF,
+ * so YMMV
+ */
+ maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize);
+ if (!maple_pmode_data) {
+ DBG("No power-mode-data !\n");
+ goto bail_noprops;
+ }
+ maple_pmode_max = psize / sizeof(u32) - 1;
+
+ /*
+ * From what I see, clock-frequency is always the maximal frequency.
+ * The current driver can not slew sysclk yet, so we really only deal
+ * with powertune steps for now. We also only implement full freq and
+ * half freq in this version. So far, I haven't yet seen a machine
+ * supporting anything else.
+ */
+ valp = of_get_property(cpunode, "clock-frequency", NULL);
+ if (!valp)
+ return -ENODEV;
+ max_freq = (*valp)/1000;
+ maple_cpu_freqs[0].frequency = max_freq;
+ maple_cpu_freqs[1].frequency = max_freq/2;
+
+ /* Force apply current frequency to make sure everything is in
+ * sync (voltage is right for example). Firmware may leave us with
+ * a strange setting ...
+ */
+ msleep(10);
+ maple_pmode_cur = -1;
+ maple_scom_switch_freq(maple_scom_query_freq());
+
+ printk(KERN_INFO "Registering Maple CPU frequency driver\n");
+ printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
+ maple_cpu_freqs[1].frequency/1000,
+ maple_cpu_freqs[0].frequency/1000,
+ maple_cpu_freqs[maple_pmode_cur].frequency/1000);
+
+ rc = cpufreq_register_driver(&maple_cpufreq_driver);
+
+ of_node_put(cpunode);
+ of_node_put(cpus);
+
+ return rc;
+
+bail_noprops:
+ of_node_put(cpunode);
+bail_cpus:
+ of_node_put(cpus);
+
+ return rc;
+}
+
+module_init(maple_cpufreq_init);
+
+
+MODULE_LICENSE("GPL");
