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1 /*
2  * Copyright 2008 Analog Devices Inc.
3  *
4  * Licensed under the GPL-2 or later.
5  */
6 
7 #include <linux/cdev.h>
8 #include <linux/device.h>
9 #include <linux/errno.h>
10 #include <linux/fs.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/platform_device.h>
14 #include <linux/types.h>
15 #include <linux/cpufreq.h>
16 
17 #include <asm/delay.h>
18 #include <asm/dpmc.h>
19 
20 #define DRIVER_NAME "bfin dpmc"
21 
22 struct bfin_dpmc_platform_data *pdata;
23 
24 /**
25  *	bfin_set_vlev - Update VLEV field in VR_CTL Reg.
26  *			Avoid BYPASS sequence
27  */
bfin_set_vlev(unsigned int vlev)28 static void bfin_set_vlev(unsigned int vlev)
29 {
30 	unsigned pll_lcnt;
31 
32 	pll_lcnt = bfin_read_PLL_LOCKCNT();
33 
34 	bfin_write_PLL_LOCKCNT(1);
35 	bfin_write_VR_CTL((bfin_read_VR_CTL() & ~VLEV) | vlev);
36 	bfin_write_PLL_LOCKCNT(pll_lcnt);
37 }
38 
39 /**
40  *	bfin_get_vlev - Get CPU specific VLEV from platform device data
41  */
bfin_get_vlev(unsigned int freq)42 static unsigned int bfin_get_vlev(unsigned int freq)
43 {
44 	int i;
45 
46 	if (!pdata)
47 		goto err_out;
48 
49 	freq >>= 16;
50 
51 	for (i = 0; i < pdata->tabsize; i++)
52 		if (freq <= (pdata->tuple_tab[i] & 0xFFFF))
53 			return pdata->tuple_tab[i] >> 16;
54 
55 err_out:
56 	printk(KERN_WARNING "DPMC: No suitable CCLK VDDINT voltage pair found\n");
57 	return VLEV_120;
58 }
59 
60 #ifdef CONFIG_CPU_FREQ
61 # ifdef CONFIG_SMP
bfin_idle_this_cpu(void * info)62 static void bfin_idle_this_cpu(void *info)
63 {
64 	unsigned long flags = 0;
65 	unsigned long iwr0, iwr1, iwr2;
66 	unsigned int cpu = smp_processor_id();
67 
68 	local_irq_save_hw(flags);
69 	bfin_iwr_set_sup0(&iwr0, &iwr1, &iwr2);
70 
71 	platform_clear_ipi(cpu, IRQ_SUPPLE_0);
72 	SSYNC();
73 	asm("IDLE;");
74 	bfin_iwr_restore(iwr0, iwr1, iwr2);
75 
76 	local_irq_restore_hw(flags);
77 }
78 
bfin_idle_cpu(void)79 static void bfin_idle_cpu(void)
80 {
81 	smp_call_function(bfin_idle_this_cpu, NULL, 0);
82 }
83 
bfin_wakeup_cpu(void)84 static void bfin_wakeup_cpu(void)
85 {
86 	unsigned int cpu;
87 	unsigned int this_cpu = smp_processor_id();
88 	cpumask_t mask;
89 
90 	cpumask_copy(&mask, cpu_online_mask);
91 	cpumask_clear_cpu(this_cpu, &mask);
92 	for_each_cpu(cpu, &mask)
93 		platform_send_ipi_cpu(cpu, IRQ_SUPPLE_0);
94 }
95 
96 # else
bfin_idle_cpu(void)97 static void bfin_idle_cpu(void) {}
bfin_wakeup_cpu(void)98 static void bfin_wakeup_cpu(void) {}
99 # endif
100 
101 static int
vreg_cpufreq_notifier(struct notifier_block * nb,unsigned long val,void * data)102 vreg_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
103 {
104 	struct cpufreq_freqs *freq = data;
105 
106 	if (freq->cpu != CPUFREQ_CPU)
107 		return 0;
108 
109 	if (val == CPUFREQ_PRECHANGE && freq->old < freq->new) {
110 		bfin_idle_cpu();
111 		bfin_set_vlev(bfin_get_vlev(freq->new));
112 		udelay(pdata->vr_settling_time); /* Wait until Volatge settled */
113 		bfin_wakeup_cpu();
114 	} else if (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) {
115 		bfin_idle_cpu();
116 		bfin_set_vlev(bfin_get_vlev(freq->new));
117 		bfin_wakeup_cpu();
118 	}
119 
120 	return 0;
121 }
122 
123 static struct notifier_block vreg_cpufreq_notifier_block = {
124 	.notifier_call	= vreg_cpufreq_notifier
125 };
126 #endif /* CONFIG_CPU_FREQ */
127 
128 /**
129  *	bfin_dpmc_probe -
130  *
131  */
bfin_dpmc_probe(struct platform_device * pdev)132 static int __devinit bfin_dpmc_probe(struct platform_device *pdev)
133 {
134 	if (pdev->dev.platform_data)
135 		pdata = pdev->dev.platform_data;
136 	else
137 		return -EINVAL;
138 
139 	return cpufreq_register_notifier(&vreg_cpufreq_notifier_block,
140 					 CPUFREQ_TRANSITION_NOTIFIER);
141 }
142 
143 /**
144  *	bfin_dpmc_remove -
145  */
bfin_dpmc_remove(struct platform_device * pdev)146 static int __devexit bfin_dpmc_remove(struct platform_device *pdev)
147 {
148 	pdata = NULL;
149 	return cpufreq_unregister_notifier(&vreg_cpufreq_notifier_block,
150 					 CPUFREQ_TRANSITION_NOTIFIER);
151 }
152 
153 struct platform_driver bfin_dpmc_device_driver = {
154 	.probe   = bfin_dpmc_probe,
155 	.remove  = __devexit_p(bfin_dpmc_remove),
156 	.driver  = {
157 		.name = DRIVER_NAME,
158 	}
159 };
160 
161 /**
162  *	bfin_dpmc_init - Init driver
163  */
bfin_dpmc_init(void)164 static int __init bfin_dpmc_init(void)
165 {
166 	return platform_driver_register(&bfin_dpmc_device_driver);
167 }
168 module_init(bfin_dpmc_init);
169 
170 /**
171  *	bfin_dpmc_exit - break down driver
172  */
bfin_dpmc_exit(void)173 static void __exit bfin_dpmc_exit(void)
174 {
175 	platform_driver_unregister(&bfin_dpmc_device_driver);
176 }
177 module_exit(bfin_dpmc_exit);
178 
179 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
180 MODULE_DESCRIPTION("cpu power management driver for Blackfin");
181 MODULE_LICENSE("GPL");
182