1 /*
2 * arch/arm/mach-at91/pm.c
3 * AT91 Power Management
4 *
5 * Copyright (C) 2005 David Brownell
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 */
12
13 #include <linux/suspend.h>
14 #include <linux/sched.h>
15 #include <linux/proc_fs.h>
16 #include <linux/interrupt.h>
17 #include <linux/sysfs.h>
18 #include <linux/module.h>
19 #include <linux/platform_device.h>
20
21 #include <asm/io.h>
22 #include <asm/irq.h>
23 #include <asm/atomic.h>
24 #include <asm/mach/time.h>
25 #include <asm/mach/irq.h>
26 #include <asm/mach-types.h>
27
28 #include <asm/arch/at91_pmc.h>
29 #include <asm/arch/at91rm9200_mc.h>
30 #include <asm/arch/gpio.h>
31 #include <asm/arch/cpu.h>
32
33 #include "generic.h"
34
35
36 static int at91_pm_valid_state(suspend_state_t state)
37 {
38 switch (state) {
39 case PM_SUSPEND_ON:
40 case PM_SUSPEND_STANDBY:
41 case PM_SUSPEND_MEM:
42 return 1;
43
44 default:
45 return 0;
46 }
47 }
48
49
50 static suspend_state_t target_state;
51
52 /*
53 * Called after processes are frozen, but before we shutdown devices.
54 */
55 static int at91_pm_begin(suspend_state_t state)
56 {
57 target_state = state;
58 return 0;
59 }
60
61 /*
62 * Verify that all the clocks are correct before entering
63 * slow-clock mode.
64 */
65 static int at91_pm_verify_clocks(void)
66 {
67 unsigned long scsr;
68 int i;
69
70 scsr = at91_sys_read(AT91_PMC_SCSR);
71
72 /* USB must not be using PLLB */
73 if (cpu_is_at91rm9200()) {
74 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
75 pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
76 return 0;
77 }
78 } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()) {
79 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
80 pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
81 return 0;
82 }
83 } else if (cpu_is_at91cap9()) {
84 if ((scsr & AT91CAP9_PMC_UHP) != 0) {
85 pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
86 return 0;
87 }
88 }
89
90 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
91 /* PCK0..PCK3 must be disabled, or configured to use clk32k */
92 for (i = 0; i < 4; i++) {
93 u32 css;
94
95 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
96 continue;
97
98 css = at91_sys_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
99 if (css != AT91_PMC_CSS_SLOW) {
100 pr_debug("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
101 return 0;
102 }
103 }
104 #endif
105
106 return 1;
107 }
108
109 /*
110 * Call this from platform driver suspend() to see how deeply to suspend.
111 * For example, some controllers (like OHCI) need one of the PLL clocks
112 * in order to act as a wakeup source, and those are not available when
113 * going into slow clock mode.
114 *
115 * REVISIT: generalize as clk_will_be_available(clk)? Other platforms have
116 * the very same problem (but not using at91 main_clk), and it'd be better
117 * to add one generic API rather than lots of platform-specific ones.
118 */
119 int at91_suspend_entering_slow_clock(void)
120 {
121 return (target_state == PM_SUSPEND_MEM);
122 }
123 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
124
125
126 static void (*slow_clock)(void);
127
128
129 static int at91_pm_enter(suspend_state_t state)
130 {
131 at91_gpio_suspend();
132 at91_irq_suspend();
133
134 pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
135 /* remember all the always-wake irqs */
136 (at91_sys_read(AT91_PMC_PCSR)
137 | (1 << AT91_ID_FIQ)
138 | (1 << AT91_ID_SYS)
139 | (at91_extern_irq))
140 & at91_sys_read(AT91_AIC_IMR),
141 state);
142
143 switch (state) {
144 /*
145 * Suspend-to-RAM is like STANDBY plus slow clock mode, so
146 * drivers must suspend more deeply: only the master clock
147 * controller may be using the main oscillator.
148 */
149 case PM_SUSPEND_MEM:
150 /*
151 * Ensure that clocks are in a valid state.
152 */
153 if (!at91_pm_verify_clocks())
154 goto error;
155
156 /*
157 * Enter slow clock mode by switching over to clk32k and
158 * turning off the main oscillator; reverse on wakeup.
159 */
160 if (slow_clock) {
161 slow_clock();
162 break;
163 } else {
164 /* DEVELOPMENT ONLY */
165 pr_info("AT91: PM - no slow clock mode yet ...\n");
166 /* FALLTHROUGH leaving master clock alone */
167 }
168
169 /*
170 * STANDBY mode has *all* drivers suspended; ignores irqs not
171 * marked as 'wakeup' event sources; and reduces DRAM power.
172 * But otherwise it's identical to PM_SUSPEND_ON: cpu idle, and
173 * nothing fancy done with main or cpu clocks.
174 */
175 case PM_SUSPEND_STANDBY:
176 /*
177 * NOTE: the Wait-for-Interrupt instruction needs to be
178 * in icache so the SDRAM stays in self-refresh mode until
179 * the wakeup IRQ occurs.
180 */
181 asm("b 1f; .align 5; 1:");
182 asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */
183 at91_sys_write(AT91_SDRAMC_SRR, 1); /* self-refresh mode */
184 /* fall though to next state */
185
186 case PM_SUSPEND_ON:
187 asm("mcr p15, 0, r0, c7, c0, 4"); /* wait for interrupt */
188 break;
189
190 default:
191 pr_debug("AT91: PM - bogus suspend state %d\n", state);
192 goto error;
193 }
194
195 pr_debug("AT91: PM - wakeup %08x\n",
196 at91_sys_read(AT91_AIC_IPR) & at91_sys_read(AT91_AIC_IMR));
197
198 error:
199 target_state = PM_SUSPEND_ON;
200 at91_irq_resume();
201 at91_gpio_resume();
202 return 0;
203 }
204
205 /*
206 * Called right prior to thawing processes.
207 */
208 static void at91_pm_end(void)
209 {
210 target_state = PM_SUSPEND_ON;
211 }
212
213
214 static struct platform_suspend_ops at91_pm_ops ={
215 .valid = at91_pm_valid_state,
216 .begin = at91_pm_begin,
217 .enter = at91_pm_enter,
218 .end = at91_pm_end,
219 };
220
221 static int __init at91_pm_init(void)
222 {
223 printk("AT91: Power Management\n");
224
225 #ifdef CONFIG_AT91_PM_SLOW_CLOCK
226 /* REVISIT allocations of SRAM should be dynamically managed.
227 * FIQ handlers and other components will want SRAM/TCM too...
228 */
229 slow_clock = (void *) (AT91_VA_BASE_SRAM + (3 * SZ_4K));
230 memcpy(slow_clock, at91rm9200_slow_clock, at91rm9200_slow_clock_sz);
231 #endif
232
233 /* Disable SDRAM low-power mode. Cannot be used with self-refresh. */
234 at91_sys_write(AT91_SDRAMC_LPR, 0);
235
236 suspend_set_ops(&at91_pm_ops);
237
238 return 0;
239 }
240 arch_initcall(at91_pm_init);
241
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