1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * OMAP2xxx DVFS virtual clock functions
4  *
5  * Copyright (C) 2005-2008, 2012 Texas Instruments, Inc.
6  * Copyright (C) 2004-2010 Nokia Corporation
7  *
8  * Contacts:
9  * Richard Woodruff <r-woodruff2@ti.com>
10  * Paul Walmsley
11  *
12  * Based on earlier work by Tuukka Tikkanen, Tony Lindgren,
13  * Gordon McNutt and RidgeRun, Inc.
14  *
15  * XXX Some of this code should be replaceable by the upcoming OPP layer
16  * code.  However, some notion of "rate set" is probably still necessary
17  * for OMAP2xxx at least.  Rate sets should be generalized so they can be
18  * used for any OMAP chip, not just OMAP2xxx.  In particular, Richard Woodruff
19  * has in the past expressed a preference to use rate sets for OPP changes,
20  * rather than dynamically recalculating the clock tree, so if someone wants
21  * this badly enough to write the code to handle it, we should support it
22  * as an option.
23  */
24 #undef DEBUG
25 
26 #include <linux/kernel.h>
27 #include <linux/errno.h>
28 #include <linux/clk.h>
29 #include <linux/io.h>
30 #include <linux/cpufreq.h>
31 #include <linux/slab.h>
32 
33 #include "soc.h"
34 #include "clock.h"
35 #include "clock2xxx.h"
36 #include "opp2xxx.h"
37 #include "cm2xxx.h"
38 #include "cm-regbits-24xx.h"
39 #include "sdrc.h"
40 #include "sram.h"
41 
42 const struct prcm_config *curr_prcm_set;
43 const struct prcm_config *rate_table;
44 
45 /*
46  * sys_ck_rate: the rate of the external high-frequency clock
47  * oscillator on the board.  Set by the SoC-specific clock init code.
48  * Once set during a boot, will not change.
49  */
50 static unsigned long sys_ck_rate;
51 
52 /**
53  * omap2_table_mpu_recalc - just return the MPU speed
54  * @clk: virt_prcm_set struct clk
55  *
56  * Set virt_prcm_set's rate to the mpu_speed field of the current PRCM set.
57  */
omap2_table_mpu_recalc(struct clk_hw * clk,unsigned long parent_rate)58 unsigned long omap2_table_mpu_recalc(struct clk_hw *clk,
59 				     unsigned long parent_rate)
60 {
61 	return curr_prcm_set->mpu_speed;
62 }
63 
64 /*
65  * Look for a rate equal or less than the target rate given a configuration set.
66  *
67  * What's not entirely clear is "which" field represents the key field.
68  * Some might argue L3-DDR, others ARM, others IVA. This code is simple and
69  * just uses the ARM rates.
70  */
omap2_round_to_table_rate(struct clk_hw * hw,unsigned long rate,unsigned long * parent_rate)71 long omap2_round_to_table_rate(struct clk_hw *hw, unsigned long rate,
72 			       unsigned long *parent_rate)
73 {
74 	const struct prcm_config *ptr;
75 	long highest_rate;
76 
77 	highest_rate = -EINVAL;
78 
79 	for (ptr = rate_table; ptr->mpu_speed; ptr++) {
80 		if (!(ptr->flags & cpu_mask))
81 			continue;
82 		if (ptr->xtal_speed != sys_ck_rate)
83 			continue;
84 
85 		highest_rate = ptr->mpu_speed;
86 
87 		/* Can check only after xtal frequency check */
88 		if (ptr->mpu_speed <= rate)
89 			break;
90 	}
91 	return highest_rate;
92 }
93 
94 /* Sets basic clocks based on the specified rate */
omap2_select_table_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)95 int omap2_select_table_rate(struct clk_hw *hw, unsigned long rate,
96 			    unsigned long parent_rate)
97 {
98 	u32 cur_rate, done_rate, bypass = 0;
99 	const struct prcm_config *prcm;
100 	unsigned long found_speed = 0;
101 	unsigned long flags;
102 
103 	for (prcm = rate_table; prcm->mpu_speed; prcm++) {
104 		if (!(prcm->flags & cpu_mask))
105 			continue;
106 
107 		if (prcm->xtal_speed != sys_ck_rate)
108 			continue;
109 
110 		if (prcm->mpu_speed <= rate) {
111 			found_speed = prcm->mpu_speed;
112 			break;
113 		}
114 	}
115 
116 	if (!found_speed) {
117 		printk(KERN_INFO "Could not set MPU rate to %luMHz\n",
118 		       rate / 1000000);
119 		return -EINVAL;
120 	}
121 
122 	curr_prcm_set = prcm;
123 	cur_rate = omap2xxx_clk_get_core_rate();
124 
125 	if (prcm->dpll_speed == cur_rate / 2) {
126 		omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL, 1);
127 	} else if (prcm->dpll_speed == cur_rate * 2) {
128 		omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL_X2, 1);
129 	} else if (prcm->dpll_speed != cur_rate) {
130 		local_irq_save(flags);
131 
132 		if (prcm->dpll_speed == prcm->xtal_speed)
133 			bypass = 1;
134 
135 		if ((prcm->cm_clksel2_pll & OMAP24XX_CORE_CLK_SRC_MASK) ==
136 		    CORE_CLK_SRC_DPLL_X2)
137 			done_rate = CORE_CLK_SRC_DPLL_X2;
138 		else
139 			done_rate = CORE_CLK_SRC_DPLL;
140 
141 		omap2xxx_cm_set_mod_dividers(prcm->cm_clksel_mpu,
142 					     prcm->cm_clksel_dsp,
143 					     prcm->cm_clksel_gfx,
144 					     prcm->cm_clksel1_core,
145 					     prcm->cm_clksel_mdm);
146 
147 		/* x2 to enter omap2xxx_sdrc_init_params() */
148 		omap2xxx_sdrc_reprogram(CORE_CLK_SRC_DPLL_X2, 1);
149 
150 		omap2_set_prcm(prcm->cm_clksel1_pll, prcm->base_sdrc_rfr,
151 			       bypass);
152 
153 		omap2xxx_sdrc_init_params(omap2xxx_sdrc_dll_is_unlocked());
154 		omap2xxx_sdrc_reprogram(done_rate, 0);
155 
156 		local_irq_restore(flags);
157 	}
158 
159 	return 0;
160 }
161 
162 /**
163  * omap2xxx_clkt_vps_check_bootloader_rate - determine which of the rate
164  * table sets matches the current CORE DPLL hardware rate
165  *
166  * Check the MPU rate set by bootloader.  Sets the 'curr_prcm_set'
167  * global to point to the active rate set when found; otherwise, sets
168  * it to NULL.  No return value;
169  */
omap2xxx_clkt_vps_check_bootloader_rates(void)170 void omap2xxx_clkt_vps_check_bootloader_rates(void)
171 {
172 	const struct prcm_config *prcm = NULL;
173 	unsigned long rate;
174 
175 	rate = omap2xxx_clk_get_core_rate();
176 	for (prcm = rate_table; prcm->mpu_speed; prcm++) {
177 		if (!(prcm->flags & cpu_mask))
178 			continue;
179 		if (prcm->xtal_speed != sys_ck_rate)
180 			continue;
181 		if (prcm->dpll_speed <= rate)
182 			break;
183 	}
184 	curr_prcm_set = prcm;
185 }
186 
187 /**
188  * omap2xxx_clkt_vps_late_init - store a copy of the sys_ck rate
189  *
190  * Store a copy of the sys_ck rate for later use by the OMAP2xxx DVFS
191  * code.  (The sys_ck rate does not -- or rather, must not -- change
192  * during kernel runtime.)  Must be called after we have a valid
193  * sys_ck rate, but before the virt_prcm_set clock rate is
194  * recalculated.  No return value.
195  */
omap2xxx_clkt_vps_late_init(void)196 void omap2xxx_clkt_vps_late_init(void)
197 {
198 	struct clk *c;
199 
200 	c = clk_get(NULL, "sys_ck");
201 	if (IS_ERR(c)) {
202 		WARN(1, "could not locate sys_ck\n");
203 	} else {
204 		sys_ck_rate = clk_get_rate(c);
205 		clk_put(c);
206 	}
207 }
208 
209 #ifdef CONFIG_OF
210 #include <linux/clk-provider.h>
211 #include <linux/clkdev.h>
212 
213 static const struct clk_ops virt_prcm_set_ops = {
214 	.recalc_rate	= &omap2_table_mpu_recalc,
215 	.set_rate	= &omap2_select_table_rate,
216 	.round_rate	= &omap2_round_to_table_rate,
217 };
218 
219 /**
220  * omap2xxx_clkt_vps_init - initialize virt_prcm_set clock
221  *
222  * Does a manual init for the virtual prcm DVFS clock for OMAP2. This
223  * function is called only from omap2 DT clock init, as the virtual
224  * node is not modelled in the DT clock data.
225  */
omap2xxx_clkt_vps_init(void)226 void omap2xxx_clkt_vps_init(void)
227 {
228 	struct clk_init_data init = { NULL };
229 	struct clk_hw_omap *hw = NULL;
230 	struct clk *clk;
231 	const char *parent_name = "mpu_ck";
232 
233 	omap2xxx_clkt_vps_late_init();
234 	omap2xxx_clkt_vps_check_bootloader_rates();
235 
236 	hw = kzalloc(sizeof(*hw), GFP_KERNEL);
237 	if (!hw)
238 		return;
239 	init.name = "virt_prcm_set";
240 	init.ops = &virt_prcm_set_ops;
241 	init.parent_names = &parent_name;
242 	init.num_parents = 1;
243 
244 	hw->hw.init = &init;
245 
246 	clk = clk_register(NULL, &hw->hw);
247 	if (IS_ERR(clk)) {
248 		printk(KERN_ERR "Failed to register clock\n");
249 		kfree(hw);
250 		return;
251 	}
252 
253 	clkdev_create(clk, "cpufreq_ck", NULL);
254 }
255 #endif
256