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5d8c6658 DES |
1 | /* |
2 | * Copyright (C) 2011 Dmitry Eremin-Solenikov | |
3 | * Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org> | |
4 | * and Markus Demleitner <msdemlei@cl.uni-heidelberg.de> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * This driver adds basic cpufreq support for SMU & 970FX based G5 Macs, | |
11 | * that is iMac G5 and latest single CPU desktop. | |
12 | */ | |
13 | ||
14 | #undef DEBUG | |
15 | ||
16 | #include <linux/module.h> | |
17 | #include <linux/types.h> | |
18 | #include <linux/errno.h> | |
19 | #include <linux/kernel.h> | |
20 | #include <linux/delay.h> | |
21 | #include <linux/sched.h> | |
22 | #include <linux/cpufreq.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/completion.h> | |
25 | #include <linux/mutex.h> | |
26 | #include <linux/time.h> | |
2421d4c3 | 27 | #include <linux/of_device.h> |
5d8c6658 DES |
28 | |
29 | #define DBG(fmt...) pr_debug(fmt) | |
30 | ||
31 | /* see 970FX user manual */ | |
32 | ||
33 | #define SCOM_PCR 0x0aa001 /* PCR scom addr */ | |
34 | ||
35 | #define PCR_HILO_SELECT 0x80000000U /* 1 = PCR, 0 = PCRH */ | |
36 | #define PCR_SPEED_FULL 0x00000000U /* 1:1 speed value */ | |
37 | #define PCR_SPEED_HALF 0x00020000U /* 1:2 speed value */ | |
38 | #define PCR_SPEED_QUARTER 0x00040000U /* 1:4 speed value */ | |
39 | #define PCR_SPEED_MASK 0x000e0000U /* speed mask */ | |
40 | #define PCR_SPEED_SHIFT 17 | |
41 | #define PCR_FREQ_REQ_VALID 0x00010000U /* freq request valid */ | |
42 | #define PCR_VOLT_REQ_VALID 0x00008000U /* volt request valid */ | |
43 | #define PCR_TARGET_TIME_MASK 0x00006000U /* target time */ | |
44 | #define PCR_STATLAT_MASK 0x00001f00U /* STATLAT value */ | |
45 | #define PCR_SNOOPLAT_MASK 0x000000f0U /* SNOOPLAT value */ | |
46 | #define PCR_SNOOPACC_MASK 0x0000000fU /* SNOOPACC value */ | |
47 | ||
48 | #define SCOM_PSR 0x408001 /* PSR scom addr */ | |
49 | /* warning: PSR is a 64 bits register */ | |
50 | #define PSR_CMD_RECEIVED 0x2000000000000000U /* command received */ | |
51 | #define PSR_CMD_COMPLETED 0x1000000000000000U /* command completed */ | |
52 | #define PSR_CUR_SPEED_MASK 0x0300000000000000U /* current speed */ | |
53 | #define PSR_CUR_SPEED_SHIFT (56) | |
54 | ||
55 | /* | |
56 | * The G5 only supports two frequencies (Quarter speed is not supported) | |
57 | */ | |
58 | #define CPUFREQ_HIGH 0 | |
59 | #define CPUFREQ_LOW 1 | |
60 | ||
61 | static struct cpufreq_frequency_table maple_cpu_freqs[] = { | |
62 | {CPUFREQ_HIGH, 0}, | |
63 | {CPUFREQ_LOW, 0}, | |
64 | {0, CPUFREQ_TABLE_END}, | |
65 | }; | |
66 | ||
5d8c6658 DES |
67 | /* Power mode data is an array of the 32 bits PCR values to use for |
68 | * the various frequencies, retrieved from the device-tree | |
69 | */ | |
70 | static int maple_pmode_cur; | |
71 | ||
72 | static DEFINE_MUTEX(maple_switch_mutex); | |
73 | ||
74 | static const u32 *maple_pmode_data; | |
75 | static int maple_pmode_max; | |
76 | ||
77 | /* | |
78 | * SCOM based frequency switching for 970FX rev3 | |
79 | */ | |
80 | static int maple_scom_switch_freq(int speed_mode) | |
81 | { | |
82 | unsigned long flags; | |
83 | int to; | |
84 | ||
85 | local_irq_save(flags); | |
86 | ||
87 | /* Clear PCR high */ | |
88 | scom970_write(SCOM_PCR, 0); | |
89 | /* Clear PCR low */ | |
90 | scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0); | |
91 | /* Set PCR low */ | |
92 | scom970_write(SCOM_PCR, PCR_HILO_SELECT | | |
93 | maple_pmode_data[speed_mode]); | |
94 | ||
95 | /* Wait for completion */ | |
96 | for (to = 0; to < 10; to++) { | |
97 | unsigned long psr = scom970_read(SCOM_PSR); | |
98 | ||
99 | if ((psr & PSR_CMD_RECEIVED) == 0 && | |
100 | (((psr >> PSR_CUR_SPEED_SHIFT) ^ | |
101 | (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3) | |
102 | == 0) | |
103 | break; | |
104 | if (psr & PSR_CMD_COMPLETED) | |
105 | break; | |
106 | udelay(100); | |
107 | } | |
108 | ||
109 | local_irq_restore(flags); | |
110 | ||
111 | maple_pmode_cur = speed_mode; | |
112 | ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul; | |
113 | ||
114 | return 0; | |
115 | } | |
116 | ||
117 | static int maple_scom_query_freq(void) | |
118 | { | |
119 | unsigned long psr = scom970_read(SCOM_PSR); | |
120 | int i; | |
121 | ||
122 | for (i = 0; i <= maple_pmode_max; i++) | |
123 | if ((((psr >> PSR_CUR_SPEED_SHIFT) ^ | |
124 | (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0) | |
125 | break; | |
126 | return i; | |
127 | } | |
128 | ||
129 | /* | |
130 | * Common interface to the cpufreq core | |
131 | */ | |
132 | ||
5d8c6658 DES |
133 | static int maple_cpufreq_target(struct cpufreq_policy *policy, |
134 | unsigned int target_freq, unsigned int relation) | |
135 | { | |
136 | unsigned int newstate = 0; | |
137 | struct cpufreq_freqs freqs; | |
138 | int rc; | |
139 | ||
140 | if (cpufreq_frequency_table_target(policy, maple_cpu_freqs, | |
141 | target_freq, relation, &newstate)) | |
142 | return -EINVAL; | |
143 | ||
144 | if (maple_pmode_cur == newstate) | |
145 | return 0; | |
146 | ||
147 | mutex_lock(&maple_switch_mutex); | |
148 | ||
149 | freqs.old = maple_cpu_freqs[maple_pmode_cur].frequency; | |
150 | freqs.new = maple_cpu_freqs[newstate].frequency; | |
5d8c6658 | 151 | |
b43a7ffb | 152 | cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); |
5d8c6658 | 153 | rc = maple_scom_switch_freq(newstate); |
b43a7ffb | 154 | cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); |
5d8c6658 DES |
155 | |
156 | mutex_unlock(&maple_switch_mutex); | |
157 | ||
158 | return rc; | |
159 | } | |
160 | ||
161 | static unsigned int maple_cpufreq_get_speed(unsigned int cpu) | |
162 | { | |
163 | return maple_cpu_freqs[maple_pmode_cur].frequency; | |
164 | } | |
165 | ||
166 | static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy) | |
167 | { | |
7bfd2483 | 168 | return cpufreq_generic_init(policy, maple_cpu_freqs, 12000); |
5d8c6658 DES |
169 | } |
170 | ||
5d8c6658 DES |
171 | static struct cpufreq_driver maple_cpufreq_driver = { |
172 | .name = "maple", | |
5d8c6658 DES |
173 | .flags = CPUFREQ_CONST_LOOPS, |
174 | .init = maple_cpufreq_cpu_init, | |
b766b908 | 175 | .verify = cpufreq_generic_frequency_table_verify, |
5d8c6658 DES |
176 | .target = maple_cpufreq_target, |
177 | .get = maple_cpufreq_get_speed, | |
b766b908 | 178 | .attr = cpufreq_generic_attr, |
5d8c6658 DES |
179 | }; |
180 | ||
181 | static int __init maple_cpufreq_init(void) | |
182 | { | |
5d8c6658 DES |
183 | struct device_node *cpunode; |
184 | unsigned int psize; | |
185 | unsigned long max_freq; | |
186 | const u32 *valp; | |
187 | u32 pvr_hi; | |
188 | int rc = -ENODEV; | |
189 | ||
190 | /* | |
191 | * Behave here like powermac driver which checks machine compatibility | |
192 | * to ease merging of two drivers in future. | |
193 | */ | |
194 | if (!of_machine_is_compatible("Momentum,Maple") && | |
195 | !of_machine_is_compatible("Momentum,Apache")) | |
196 | return 0; | |
197 | ||
5d8c6658 | 198 | /* Get first CPU node */ |
2421d4c3 | 199 | cpunode = of_cpu_device_node_get(0); |
5d8c6658 DES |
200 | if (cpunode == NULL) { |
201 | printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n"); | |
2421d4c3 | 202 | goto bail_noprops; |
5d8c6658 DES |
203 | } |
204 | ||
205 | /* Check 970FX for now */ | |
206 | /* we actually don't care on which CPU to access PVR */ | |
207 | pvr_hi = PVR_VER(mfspr(SPRN_PVR)); | |
208 | if (pvr_hi != 0x3c && pvr_hi != 0x44) { | |
209 | printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n", | |
210 | pvr_hi); | |
211 | goto bail_noprops; | |
212 | } | |
213 | ||
214 | /* Look for the powertune data in the device-tree */ | |
215 | /* | |
216 | * On Maple this property is provided by PIBS in dual-processor config, | |
217 | * not provided by PIBS in CPU0 config and also not provided by SLOF, | |
218 | * so YMMV | |
219 | */ | |
220 | maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize); | |
221 | if (!maple_pmode_data) { | |
222 | DBG("No power-mode-data !\n"); | |
223 | goto bail_noprops; | |
224 | } | |
225 | maple_pmode_max = psize / sizeof(u32) - 1; | |
226 | ||
227 | /* | |
228 | * From what I see, clock-frequency is always the maximal frequency. | |
229 | * The current driver can not slew sysclk yet, so we really only deal | |
230 | * with powertune steps for now. We also only implement full freq and | |
231 | * half freq in this version. So far, I haven't yet seen a machine | |
232 | * supporting anything else. | |
233 | */ | |
234 | valp = of_get_property(cpunode, "clock-frequency", NULL); | |
235 | if (!valp) | |
236 | return -ENODEV; | |
237 | max_freq = (*valp)/1000; | |
238 | maple_cpu_freqs[0].frequency = max_freq; | |
239 | maple_cpu_freqs[1].frequency = max_freq/2; | |
240 | ||
241 | /* Force apply current frequency to make sure everything is in | |
242 | * sync (voltage is right for example). Firmware may leave us with | |
243 | * a strange setting ... | |
244 | */ | |
245 | msleep(10); | |
246 | maple_pmode_cur = -1; | |
247 | maple_scom_switch_freq(maple_scom_query_freq()); | |
248 | ||
249 | printk(KERN_INFO "Registering Maple CPU frequency driver\n"); | |
250 | printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n", | |
251 | maple_cpu_freqs[1].frequency/1000, | |
252 | maple_cpu_freqs[0].frequency/1000, | |
253 | maple_cpu_freqs[maple_pmode_cur].frequency/1000); | |
254 | ||
255 | rc = cpufreq_register_driver(&maple_cpufreq_driver); | |
256 | ||
257 | of_node_put(cpunode); | |
5d8c6658 DES |
258 | |
259 | return rc; | |
260 | ||
261 | bail_noprops: | |
262 | of_node_put(cpunode); | |
5d8c6658 DES |
263 | |
264 | return rc; | |
265 | } | |
266 | ||
267 | module_init(maple_cpufreq_init); | |
268 | ||
269 | ||
270 | MODULE_LICENSE("GPL"); |