1 /*
2  * OMAP2xxx DVFS virtual clock functions
3  *
4  * Copyright (C) 2005-2008 Texas Instruments, Inc.
5  * Copyright (C) 2004-2010 Nokia Corporation
6  *
7  * Contacts:
8  * Richard Woodruff <r-woodruff2@ti.com>
9  * Paul Walmsley
10  *
11  * Based on earlier work by Tuukka Tikkanen, Tony Lindgren,
12  * Gordon McNutt and RidgeRun, Inc.
13  *
14  * This program is free software; you can redistribute it and/or modify
15  * it under the terms of the GNU General Public License version 2 as
16  * published by the Free Software Foundation.
17  *
18  * XXX Some of this code should be replaceable by the upcoming OPP layer
19  * code.  However, some notion of "rate set" is probably still necessary
20  * for OMAP2xxx at least.  Rate sets should be generalized so they can be
21  * used for any OMAP chip, not just OMAP2xxx.  In particular, Richard Woodruff
22  * has in the past expressed a preference to use rate sets for OPP changes,
23  * rather than dynamically recalculating the clock tree, so if someone wants
24  * this badly enough to write the code to handle it, we should support it
25  * as an option.
26  */
27 #undef DEBUG
28 
29 #include <linux/kernel.h>
30 #include <linux/errno.h>
31 #include <linux/clk.h>
32 #include <linux/io.h>
33 #include <linux/cpufreq.h>
34 #include <linux/slab.h>
35 
36 #include <plat/cpu.h>
37 #include <plat/clock.h>
38 #include <plat/sram.h>
39 #include <plat/sdrc.h>
40 
41 #include "clock.h"
42 #include "clock2xxx.h"
43 #include "opp2xxx.h"
44 #include "cm2xxx_3xxx.h"
45 #include "cm-regbits-24xx.h"
46 
47 const struct prcm_config *curr_prcm_set;
48 const struct prcm_config *rate_table;
49 
50 /**
51  * omap2_table_mpu_recalc - just return the MPU speed
52  * @clk: virt_prcm_set struct clk
53  *
54  * Set virt_prcm_set's rate to the mpu_speed field of the current PRCM set.
55  */
56 unsigned long omap2_table_mpu_recalc(struct clk *clk)
57 {
58 	return curr_prcm_set->mpu_speed;
59 }
60 
61 /*
62  * Look for a rate equal or less than the target rate given a configuration set.
63  *
64  * What's not entirely clear is "which" field represents the key field.
65  * Some might argue L3-DDR, others ARM, others IVA. This code is simple and
66  * just uses the ARM rates.
67  */
68 long omap2_round_to_table_rate(struct clk *clk, unsigned long rate)
69 {
70 	const struct prcm_config *ptr;
71 	long highest_rate;
72 
73 	highest_rate = -EINVAL;
74 
75 	for (ptr = rate_table; ptr->mpu_speed; ptr++) {
76 		if (!(ptr->flags & cpu_mask))
77 			continue;
78 		if (ptr->xtal_speed != sclk->rate)
79 			continue;
80 
81 		highest_rate = ptr->mpu_speed;
82 
83 		/* Can check only after xtal frequency check */
84 		if (ptr->mpu_speed <= rate)
85 			break;
86 	}
87 	return highest_rate;
88 }
89 
90 /* Sets basic clocks based on the specified rate */
91 int omap2_select_table_rate(struct clk *clk, unsigned long rate)
92 {
93 	u32 cur_rate, done_rate, bypass = 0, tmp;
94 	const struct prcm_config *prcm;
95 	unsigned long found_speed = 0;
96 	unsigned long flags;
97 
98 	for (prcm = rate_table; prcm->mpu_speed; prcm++) {
99 		if (!(prcm->flags & cpu_mask))
100 			continue;
101 
102 		if (prcm->xtal_speed != sclk->rate)
103 			continue;
104 
105 		if (prcm->mpu_speed <= rate) {
106 			found_speed = prcm->mpu_speed;
107 			break;
108 		}
109 	}
110 
111 	if (!found_speed) {
112 		printk(KERN_INFO "Could not set MPU rate to %luMHz\n",
113 		       rate / 1000000);
114 		return -EINVAL;
115 	}
116 
117 	curr_prcm_set = prcm;
118 	cur_rate = omap2xxx_clk_get_core_rate(dclk);
119 
120 	if (prcm->dpll_speed == cur_rate / 2) {
121 		omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL, 1);
122 	} else if (prcm->dpll_speed == cur_rate * 2) {
123 		omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL_X2, 1);
124 	} else if (prcm->dpll_speed != cur_rate) {
125 		local_irq_save(flags);
126 
127 		if (prcm->dpll_speed == prcm->xtal_speed)
128 			bypass = 1;
129 
130 		if ((prcm->cm_clksel2_pll & OMAP24XX_CORE_CLK_SRC_MASK) ==
131 		    CORE_CLK_SRC_DPLL_X2)
132 			done_rate = CORE_CLK_SRC_DPLL_X2;
133 		else
134 			done_rate = CORE_CLK_SRC_DPLL;
135 
136 		/* MPU divider */
137 		omap2_cm_write_mod_reg(prcm->cm_clksel_mpu, MPU_MOD, CM_CLKSEL);
138 
139 		/* dsp + iva1 div(2420), iva2.1(2430) */
140 		omap2_cm_write_mod_reg(prcm->cm_clksel_dsp,
141 				 OMAP24XX_DSP_MOD, CM_CLKSEL);
142 
143 		omap2_cm_write_mod_reg(prcm->cm_clksel_gfx, GFX_MOD, CM_CLKSEL);
144 
145 		/* Major subsystem dividers */
146 		tmp = omap2_cm_read_mod_reg(CORE_MOD, CM_CLKSEL1) & OMAP24XX_CLKSEL_DSS2_MASK;
147 		omap2_cm_write_mod_reg(prcm->cm_clksel1_core | tmp, CORE_MOD,
148 				 CM_CLKSEL1);
149 
150 		if (cpu_is_omap2430())
151 			omap2_cm_write_mod_reg(prcm->cm_clksel_mdm,
152 					 OMAP2430_MDM_MOD, CM_CLKSEL);
153 
154 		/* x2 to enter omap2xxx_sdrc_init_params() */
155 		omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL_X2, 1);
156 
157 		omap2_set_prcm(prcm->cm_clksel1_pll, prcm->base_sdrc_rfr,
158 			       bypass);
159 
160 		omap2xxx_sdrc_init_params(omap2xxx_sdrc_dll_is_unlocked());
161 		omap2xxx_sdrc_reprogram(done_rate, 0);
162 
163 		local_irq_restore(flags);
164 	}
165 
166 	return 0;
167 }
168