[PATCH] ppc64: Add cpufreq support for SMU based G5

From: Benjamin Herrenschmidt
Date: Tue Oct 04 2005 - 00:41:51 EST

iMac G5 and latest single CPU desktop G5 (SMU based machines) have a
970FX DD3 CPU that supports frequency & vooltage switching. This patch
adds support for simple dual frequency switch. It is required for the
upcoming thermal control patch for these machines.

Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>

Index: linux-work/arch/ppc64/kernel/misc.S
===================================================================
--- linux-work.orig/arch/ppc64/kernel/misc.S 2005-09-23 12:43:21.000000000 +1000
+++ linux-work/arch/ppc64/kernel/misc.S 2005-09-29 17:03:04.000000000 +1000
@@ -616,7 +616,7 @@
isync
blr

- /*
+/*
* Do an IO access in real mode
*/
_GLOBAL(real_writeb)
@@ -649,6 +649,76 @@
#endif /* defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_MAPLE) */

/*
+ * SCOM access functions for 970 (FX only for now)
+ *
+ * unsigned long scom970_read(unsigned int address);
+ * void scom970_write(unsigned int address, unsigned long value);
+ *
+ * The address passed in is the 24 bits register address. This code
+ * is 970 specific and will not check the status bits, so you should
+ * know what you are doing.
+ */
+_GLOBAL(scom970_read)
+ /* interrupts off */
+ mfmsr r4
+ ori r0,r4,MSR_EE
+ xori r0,r0,MSR_EE
+ mtmsrd r0,1
+
+ /* rotate 24 bits SCOM address 8 bits left and mask out it's low 8 bits
+ * (including parity). On current CPUs they must be 0'd,
+ * and finally or in RW bit
+ */
+ rlwinm r3,r3,8,0,15
+ ori r3,r3,0x8000
+
+ /* do the actual scom read */
+ sync
+ mtspr SPRN_SCOMC,r3
+ isync
+ mfspr r3,SPRN_SCOMD
+ isync
+ mfspr r0,SPRN_SCOMC
+ isync
+
+ /* XXX: fixup result on some buggy 970's (ouch ! we lost a bit, bah
+ * that's the best we can do). Not implemented yet as we don't use
+ * the scom on any of the bogus CPUs yet, but may have to be done
+ * ultimately
+ */
+
+ /* restore interrupts */
+ mtmsrd r4,1
+ blr
+
+
+_GLOBAL(scom970_write)
+ /* interrupts off */
+ mfmsr r5
+ ori r0,r5,MSR_EE
+ xori r0,r0,MSR_EE
+ mtmsrd r0,1
+
+ /* rotate 24 bits SCOM address 8 bits left and mask out it's low 8 bits
+ * (including parity). On current CPUs they must be 0'd.
+ */
+
+ rlwinm r3,r3,8,0,15
+
+ sync
+ mtspr SPRN_SCOMD,r4 /* write data */
+ isync
+ mtspr SPRN_SCOMC,r3 /* write command */
+ isync
+ mfspr 3,SPRN_SCOMC
+ isync
+
+ /* restore interrupts */
+ mtmsrd r5,1
+ blr
+
+
+/*
* Create a kernel thread
* kernel_thread(fn, arg, flags)
*/
Index: linux-work/include/asm-ppc64/processor.h
===================================================================
--- linux-work.orig/include/asm-ppc64/processor.h 2005-09-23 12:44:12.000000000 +1000
+++ linux-work/include/asm-ppc64/processor.h 2005-09-27 11:42:50.000000000 +1000
@@ -177,6 +177,9 @@
#define SPRN_CTRLT 0x098
#define CTRL_RUNLATCH 0x1

+#define SPRN_SCOMC 0x114
+#define SPRN_SCOMD 0x115
+
/* Performance monitor SPRs */
#define SPRN_SIAR 780
#define SPRN_SDAR 781
@@ -536,6 +539,9 @@
}
}

+extern unsigned long scom970_read(unsigned int address);
+extern void scom970_write(unsigned int address, unsigned long value);
+
#endif /* __KERNEL__ */

#endif /* __ASSEMBLY__ */
Index: linux-work/arch/ppc64/Kconfig
===================================================================
--- linux-work.orig/arch/ppc64/Kconfig 2005-09-23 12:43:21.000000000 +1000
+++ linux-work/arch/ppc64/Kconfig 2005-09-28 10:41:27.000000000 +1000
@@ -159,6 +159,17 @@
support. As of this writing the exact hardware interface is
strongly in flux, so no good recommendation can be made.

+source "drivers/cpufreq/Kconfig"
+
+config CPU_FREQ_PMAC
+ bool "Support for Apple G5"
+ depends on CPU_FREQ && PPC_PMAC64
+ select CPU_FREQ_TABLE
+ help
+ This adds support for frequency switching on some Apple G5
+ machine. This is currently very experimental and works only
+ on some iMac G5.
+
config IBMVIO
depends on PPC_PSERIES || PPC_ISERIES
bool
Index: linux-work/arch/ppc64/kernel/Makefile
===================================================================
--- linux-work.orig/arch/ppc64/kernel/Makefile 2005-09-23 12:43:21.000000000 +1000
+++ linux-work/arch/ppc64/kernel/Makefile 2005-09-27 11:42:50.000000000 +1000
@@ -60,6 +60,7 @@
obj-$(CONFIG_PPC_PMAC) += pmac_setup.o pmac_feature.o pmac_pci.o \
pmac_time.o pmac_nvram.o pmac_low_i2c.o \
udbg_scc.o
+obj-$(CONFIG_CPU_FREQ_PMAC) += pmac_cpufreq.o

obj-$(CONFIG_PPC_MAPLE) += maple_setup.o maple_pci.o maple_time.o \
udbg_16550.o
Index: linux-work/arch/ppc64/kernel/pmac_cpufreq.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-work/arch/ppc64/kernel/pmac_cpufreq.c 2005-09-27 11:42:50.000000000 +1000
@@ -0,0 +1,297 @@
+/*
+ * Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
+ * and Markus Demleitner <msdemlei@xxxxxxxxxxxxxxxxxxxx>
+ *
+ * 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.
+ */
+
+#include <linux/config.h>
+#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/slab.h>
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/irq.h>
+#include <asm/sections.h>
+#include <asm/cputable.h>
+#include <asm/time.h>
+#include <asm/smu.h>
+
+#undef DEBUG
+
+#ifdef DEBUG
+#define DBG(fmt...) printk(fmt)
+#else
+#define DBG(fmt...)
+#endif
+
+/* 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 g5_cpu_freqs[] = {
+ {CPUFREQ_HIGH, 0},
+ {CPUFREQ_LOW, 0},
+ {0, CPUFREQ_TABLE_END},
+};
+
+static struct freq_attr* g5_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, retreived from the device-tree
+ */
+static u32 *g5_pmode_data;
+static int g5_pmode_max;
+static int g5_pmode_cur;
+
+
+static struct smu_sdbp_fvt *g5_fvt_table; /* table of op. points */
+static int g5_fvt_count; /* number of op. points */
+static int g5_fvt_cur; /* current op. point */
+
+/* ----------------- real hardware interface */
+
+static void g5_switch_volt(int speed_mode)
+{
+ struct smu_simple_cmd cmd;
+
+ DECLARE_COMPLETION(comp);
+ smu_queue_simple(&cmd, SMU_CMD_POWER_COMMAND, 8, smu_done_complete,
+ &comp, 'V', 'S', 'L', 'E', 'W',
+ 0xff, g5_fvt_cur+1, speed_mode);
+ wait_for_completion(&comp);
+}
+
+static int g5_switch_freq(int speed_mode)
+{
+ int to;
+
+ if (g5_pmode_cur == speed_mode)
+ return 0;
+
+ /* If frequency is going up, first ramp up the voltage */
+ if (speed_mode < g5_pmode_cur)
+ g5_switch_volt(speed_mode);
+
+ /* 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 |
+ g5_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) ^
+ (g5_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3)
+ == 0)
+ break;
+ if (psr & PSR_CMD_COMPLETED)
+ break;
+ udelay(100);
+ }
+
+ /* If frequency is going down, last ramp the voltage */
+ if (speed_mode > g5_pmode_cur)
+ g5_switch_volt(speed_mode);
+
+ g5_pmode_cur = speed_mode;
+ ppc_proc_freq = g5_cpu_freqs[speed_mode].frequency * 1000ul;
+
+ return 0;
+}
+
+static int g5_query_freq(void)
+{
+ unsigned long psr = scom970_read(SCOM_PSR);
+ int i;
+
+ for (i = 0; i <= g5_pmode_max; i++)
+ if ((((psr >> PSR_CUR_SPEED_SHIFT) ^
+ (g5_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0)
+ break;
+ return i;
+}
+
+/* ----------------- cpufreq bookkeeping */
+static int __pmac g5_cpufreq_verify(struct cpufreq_policy *policy)
+{
+ return cpufreq_frequency_table_verify(policy, g5_cpu_freqs);
+}
+
+static int __pmac g5_cpufreq_target(struct cpufreq_policy *policy,
+ unsigned int target_freq, unsigned int relation)
+{
+ unsigned int newstate = 0;
+
+ if (cpufreq_frequency_table_target(policy, g5_cpu_freqs,
+ target_freq, relation, &newstate))
+ return -EINVAL;
+
+ return g5_switch_freq(newstate);
+}
+
+static int __pmac g5_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+ if (policy->cpu != 0)
+ return -ENODEV;
+
+ policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+ policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
+ policy->cur = g5_cpu_freqs[g5_query_freq()].frequency;
+ cpufreq_frequency_table_get_attr(g5_cpu_freqs, policy->cpu);
+
+ return cpufreq_frequency_table_cpuinfo(policy,
+ g5_cpu_freqs);
+}
+
+
+static struct cpufreq_driver g5_cpufreq_driver = {
+ .name = "powermac",
+ .owner = THIS_MODULE,
+ .flags = CPUFREQ_CONST_LOOPS,
+ .init = g5_cpufreq_cpu_init,
+ .verify = g5_cpufreq_verify,
+ .target = g5_cpufreq_target,
+ .attr = g5_cpu_freqs_attr,
+};
+
+
+static int __init g5_cpufreq_init(void)
+{
+ struct device_node *cpunode;
+ unsigned int psize, ssize;
+ struct smu_sdbp_header *shdr;
+ unsigned long max_freq;
+ u32 *valp;
+ int rc = -ENODEV;
+
+ /* Look for CPU and SMU nodes */
+ cpunode = of_find_node_by_type(NULL, "cpu");
+ if (!cpunode) {
+ DBG("No CPU node !\n");
+ return -ENODEV;
+ }
+
+ /* Check 970FX for now */
+ valp = (u32 *)get_property(cpunode, "cpu-version", NULL);
+ if (!valp) {
+ DBG("No cpu-version property !\n");
+ goto bail_noprops;
+ }
+ if (((*valp) >> 16) != 0x3c) {
+ DBG("Wrong CPU version: %08x\n", *valp);
+ goto bail_noprops;
+ }
+
+ /* Look for the powertune data in the device-tree */
+ g5_pmode_data = (u32 *)get_property(cpunode, "power-mode-data",&psize);
+ if (!g5_pmode_data) {
+ DBG("No power-mode-data !\n");
+ goto bail_noprops;
+ }
+ g5_pmode_max = psize / sizeof(u32) - 1;
+
+ /* Look for the FVT table */
+ shdr = smu_get_sdb_partition(SMU_SDB_FVT_ID, NULL);
+ if (!shdr)
+ goto bail_noprops;
+ g5_fvt_table = (struct smu_sdbp_fvt *)&shdr[1];
+ ssize = (shdr->len * sizeof(u32)) - sizeof(struct smu_sdbp_header);
+ g5_fvt_count = ssize / sizeof(struct smu_sdbp_fvt);
+ g5_fvt_cur = 0;
+
+ /* Sanity checking */
+ if (g5_fvt_count < 1 || g5_pmode_max < 1)
+ goto bail_noprops;
+
+ /*
+ * 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 = (u32 *)get_property(cpunode, "clock-frequency", NULL);
+ if (!valp)
+ return -ENODEV;
+ max_freq = (*valp)/1000;
+ g5_cpu_freqs[0].frequency = max_freq;
+ g5_cpu_freqs[1].frequency = max_freq/2;
+
+ /* Check current frequency */
+ g5_pmode_cur = g5_query_freq();
+ if (g5_pmode_cur > 1) {
+ /* We don't support anything but 1:1 and 1:2, fixup ... */
+ g5_switch_freq(1);
+ g5_pmode_cur = 1;
+ }
+
+ printk(KERN_INFO "Registering G5 CPU frequency driver\n");
+ printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
+ g5_cpu_freqs[1].frequency/1000,
+ g5_cpu_freqs[0].frequency/1000,
+ g5_cpu_freqs[g5_pmode_cur].frequency/1000);
+
+ rc = cpufreq_register_driver(&g5_cpufreq_driver);
+
+ /* We keep the CPU node on hold... hopefully, Apple G5 don't have
+ * hotplug CPU with a dynamic device-tree ...
+ */
+ return rc;
+
+ bail_noprops:
+ of_node_put(cpunode);
+
+ return rc;
+}
+
+module_init(g5_cpufreq_init);
+
+
+MODULE_LICENSE("GPL");
Index: linux-work/drivers/macintosh/smu.c
===================================================================
--- linux-work.orig/drivers/macintosh/smu.c 2005-09-26 11:48:36.000000000 +1000
+++ linux-work/drivers/macintosh/smu.c 2005-09-29 16:56:59.000000000 +1000
@@ -843,6 +843,18 @@
return 0;
}

+struct smu_sdbp_header *smu_get_sdb_partition(int id, unsigned int *size)
+{
+ char pname[32];
+
+ if (!smu)
+ return NULL;
+
+ sprintf(pname, "sdb-partition-%02x", id);
+ return (struct smu_sdbp_header *)get_property(smu->of_node,
+ pname, size);
+}
+EXPORT_SYMBOL(smu_get_sdb_partition);


/*
Index: linux-work/include/asm-ppc64/smu.h
===================================================================
--- linux-work.orig/include/asm-ppc64/smu.h 2005-09-26 11:48:37.000000000 +1000
+++ linux-work/include/asm-ppc64/smu.h 2005-09-29 16:56:59.000000000 +1000
@@ -144,7 +144,11 @@
* - lenght 8 ("VSLEWxyz") has 3 additional bytes appended, and is
* used to set the voltage slewing point. The SMU replies with "DONE"
* I yet have to figure out their exact meaning of those 3 bytes in
- * both cases.
+ * both cases. They seem to be:
+ * x = processor mask
+ * y = op. point index
+ * z = processor freq. step index
+ * I haven't yet decyphered result codes
*
*/
#define SMU_CMD_POWER_COMMAND 0xaa
@@ -244,6 +248,7 @@
*/
extern void smu_done_complete(struct smu_cmd *cmd, void *misc);

+
/*
* Synchronous helpers. Will spin-wait for completion of a command
*/
@@ -334,6 +339,59 @@
#endif /* __KERNEL__ */

/*
+ * - SMU "sdb" partitions informations -
+ */
+
+
+/*
+ * Partition header format
+ */
+struct smu_sdbp_header {
+ __u8 id;
+ __u8 len;
+ __u8 version;
+ __u8 flags;
+};
+
+/*
+ * 32 bits integers are usually encoded with 2x16 bits swapped,
+ * this demangles them
+ */
+#define SMU_U32_MIX(x) ((((x) << 16) & 0xffff0000u) | (((x) >> 16) & 0xffffu))
+
+/* This is the definition of the SMU sdb-partition-0x12 table (called
+ * CPU F/V/T operating points in Darwin). The definition for all those
+ * SMU tables should be moved to some separate file
+ */
+#define SMU_SDB_FVT_ID 0x12
+
+struct smu_sdbp_fvt {
+ __u32 sysclk; /* Base SysClk frequency in Hz for
+ * this operating point
+ */
+ __u8 pad;
+ __u8 maxtemp; /* Max temp. supported by this
+ * operating point
+ */
+
+ __u16 volts[3]; /* CPU core voltage for the 3
+ * PowerTune modes, a mode with
+ * 0V = not supported.
+ */
+};
+
+#ifdef __KERNEL__
+/*
+ * This returns the pointer to an SMU "sdb" partition data or NULL
+ * if not found. The data format is described below
+ */
+extern struct smu_sdbp_header *smu_get_sdb_partition(int id,
+ unsigned int *size);
+
+#endif /* __KERNEL__ */
+
+
+/*
* - Userland interface -
*/

@@ -376,4 +434,5 @@
__u32 reply_len; /* Lenght of data follwing */
};

+
#endif /* _SMU_H */


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/