242 lines
6.5 KiB
C
242 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2011 Dmitry Eremin-Solenikov
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* Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
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* and Markus Demleitner <msdemlei@cl.uni-heidelberg.de>
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*
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* This driver adds basic cpufreq support for SMU & 970FX based G5 Macs,
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* that is iMac G5 and latest single CPU desktop.
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*/
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#undef DEBUG
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/delay.h>
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#include <linux/sched.h>
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#include <linux/cpufreq.h>
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#include <linux/init.h>
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#include <linux/completion.h>
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#include <linux/mutex.h>
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#include <linux/time.h>
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#include <linux/of_device.h>
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#define DBG(fmt...) pr_debug(fmt)
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/* see 970FX user manual */
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#define SCOM_PCR 0x0aa001 /* PCR scom addr */
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#define PCR_HILO_SELECT 0x80000000U /* 1 = PCR, 0 = PCRH */
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#define PCR_SPEED_FULL 0x00000000U /* 1:1 speed value */
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#define PCR_SPEED_HALF 0x00020000U /* 1:2 speed value */
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#define PCR_SPEED_QUARTER 0x00040000U /* 1:4 speed value */
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#define PCR_SPEED_MASK 0x000e0000U /* speed mask */
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#define PCR_SPEED_SHIFT 17
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#define PCR_FREQ_REQ_VALID 0x00010000U /* freq request valid */
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#define PCR_VOLT_REQ_VALID 0x00008000U /* volt request valid */
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#define PCR_TARGET_TIME_MASK 0x00006000U /* target time */
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#define PCR_STATLAT_MASK 0x00001f00U /* STATLAT value */
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#define PCR_SNOOPLAT_MASK 0x000000f0U /* SNOOPLAT value */
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#define PCR_SNOOPACC_MASK 0x0000000fU /* SNOOPACC value */
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#define SCOM_PSR 0x408001 /* PSR scom addr */
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/* warning: PSR is a 64 bits register */
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#define PSR_CMD_RECEIVED 0x2000000000000000U /* command received */
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#define PSR_CMD_COMPLETED 0x1000000000000000U /* command completed */
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#define PSR_CUR_SPEED_MASK 0x0300000000000000U /* current speed */
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#define PSR_CUR_SPEED_SHIFT (56)
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/*
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* The G5 only supports two frequencies (Quarter speed is not supported)
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*/
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#define CPUFREQ_HIGH 0
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#define CPUFREQ_LOW 1
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static struct cpufreq_frequency_table maple_cpu_freqs[] = {
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{0, CPUFREQ_HIGH, 0},
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{0, CPUFREQ_LOW, 0},
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{0, 0, CPUFREQ_TABLE_END},
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};
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/* Power mode data is an array of the 32 bits PCR values to use for
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* the various frequencies, retrieved from the device-tree
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*/
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static int maple_pmode_cur;
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static const u32 *maple_pmode_data;
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static int maple_pmode_max;
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/*
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* SCOM based frequency switching for 970FX rev3
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*/
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static int maple_scom_switch_freq(int speed_mode)
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{
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unsigned long flags;
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int to;
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local_irq_save(flags);
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/* Clear PCR high */
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scom970_write(SCOM_PCR, 0);
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/* Clear PCR low */
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scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0);
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/* Set PCR low */
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scom970_write(SCOM_PCR, PCR_HILO_SELECT |
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maple_pmode_data[speed_mode]);
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/* Wait for completion */
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for (to = 0; to < 10; to++) {
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unsigned long psr = scom970_read(SCOM_PSR);
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if ((psr & PSR_CMD_RECEIVED) == 0 &&
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(((psr >> PSR_CUR_SPEED_SHIFT) ^
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(maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3)
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== 0)
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break;
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if (psr & PSR_CMD_COMPLETED)
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break;
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udelay(100);
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}
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local_irq_restore(flags);
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maple_pmode_cur = speed_mode;
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ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul;
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return 0;
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}
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static int maple_scom_query_freq(void)
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{
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unsigned long psr = scom970_read(SCOM_PSR);
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int i;
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for (i = 0; i <= maple_pmode_max; i++)
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if ((((psr >> PSR_CUR_SPEED_SHIFT) ^
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(maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0)
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break;
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return i;
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}
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/*
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* Common interface to the cpufreq core
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*/
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static int maple_cpufreq_target(struct cpufreq_policy *policy,
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unsigned int index)
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{
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return maple_scom_switch_freq(index);
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}
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static unsigned int maple_cpufreq_get_speed(unsigned int cpu)
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{
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return maple_cpu_freqs[maple_pmode_cur].frequency;
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}
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static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy)
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{
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cpufreq_generic_init(policy, maple_cpu_freqs, 12000);
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return 0;
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}
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static struct cpufreq_driver maple_cpufreq_driver = {
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.name = "maple",
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.flags = CPUFREQ_CONST_LOOPS,
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.init = maple_cpufreq_cpu_init,
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = maple_cpufreq_target,
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.get = maple_cpufreq_get_speed,
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.attr = cpufreq_generic_attr,
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};
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static int __init maple_cpufreq_init(void)
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{
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struct device_node *cpunode;
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unsigned int psize;
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unsigned long max_freq;
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const u32 *valp;
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u32 pvr_hi;
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int rc = -ENODEV;
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/*
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* Behave here like powermac driver which checks machine compatibility
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* to ease merging of two drivers in future.
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*/
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if (!of_machine_is_compatible("Momentum,Maple") &&
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!of_machine_is_compatible("Momentum,Apache"))
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return 0;
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/* Get first CPU node */
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cpunode = of_cpu_device_node_get(0);
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if (cpunode == NULL) {
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pr_err("Can't find any CPU 0 node\n");
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goto bail_noprops;
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}
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/* Check 970FX for now */
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/* we actually don't care on which CPU to access PVR */
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pvr_hi = PVR_VER(mfspr(SPRN_PVR));
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if (pvr_hi != 0x3c && pvr_hi != 0x44) {
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pr_err("Unsupported CPU version (%x)\n", pvr_hi);
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goto bail_noprops;
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}
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/* Look for the powertune data in the device-tree */
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/*
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* On Maple this property is provided by PIBS in dual-processor config,
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* not provided by PIBS in CPU0 config and also not provided by SLOF,
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* so YMMV
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*/
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maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize);
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if (!maple_pmode_data) {
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DBG("No power-mode-data !\n");
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goto bail_noprops;
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}
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maple_pmode_max = psize / sizeof(u32) - 1;
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/*
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* From what I see, clock-frequency is always the maximal frequency.
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* The current driver can not slew sysclk yet, so we really only deal
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* with powertune steps for now. We also only implement full freq and
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* half freq in this version. So far, I haven't yet seen a machine
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* supporting anything else.
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*/
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valp = of_get_property(cpunode, "clock-frequency", NULL);
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if (!valp)
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goto bail_noprops;
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max_freq = (*valp)/1000;
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maple_cpu_freqs[0].frequency = max_freq;
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maple_cpu_freqs[1].frequency = max_freq/2;
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/* Force apply current frequency to make sure everything is in
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* sync (voltage is right for example). Firmware may leave us with
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* a strange setting ...
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*/
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msleep(10);
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maple_pmode_cur = -1;
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maple_scom_switch_freq(maple_scom_query_freq());
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pr_info("Registering Maple CPU frequency driver\n");
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pr_info("Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
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maple_cpu_freqs[1].frequency/1000,
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maple_cpu_freqs[0].frequency/1000,
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maple_cpu_freqs[maple_pmode_cur].frequency/1000);
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rc = cpufreq_register_driver(&maple_cpufreq_driver);
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bail_noprops:
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of_node_put(cpunode);
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return rc;
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}
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module_init(maple_cpufreq_init);
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MODULE_LICENSE("GPL");
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