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1 | /* |
2 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
3 | * Author: Thomas Abraham <thomas.ab@samsung.com> | |
4 | * | |
5 | * Copyright (c) 2015 Samsung Electronics Co., Ltd. | |
6 | * Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
12 | * This file contains the utility function to register CPU clock for Samsung | |
13 | * Exynos platforms. A CPU clock is defined as a clock supplied to a CPU or a | |
14 | * group of CPUs. The CPU clock is typically derived from a hierarchy of clock | |
15 | * blocks which includes mux and divider blocks. There are a number of other | |
16 | * auxiliary clocks supplied to the CPU domain such as the debug blocks and AXI | |
17 | * clock for CPU domain. The rates of these auxiliary clocks are related to the | |
18 | * CPU clock rate and this relation is usually specified in the hardware manual | |
19 | * of the SoC or supplied after the SoC characterization. | |
20 | * | |
21 | * The below implementation of the CPU clock allows the rate changes of the CPU | |
22 | * clock and the corresponding rate changes of the auxillary clocks of the CPU | |
23 | * domain. The platform clock driver provides a clock register configuration | |
24 | * for each configurable rate which is then used to program the clock hardware | |
25 | * registers to acheive a fast co-oridinated rate change for all the CPU domain | |
26 | * clocks. | |
27 | * | |
28 | * On a rate change request for the CPU clock, the rate change is propagated | |
29 | * upto the PLL supplying the clock to the CPU domain clock blocks. While the | |
30 | * CPU domain PLL is reconfigured, the CPU domain clocks are driven using an | |
31 | * alternate clock source. If required, the alternate clock source is divided | |
32 | * down in order to keep the output clock rate within the previous OPP limits. | |
33 | */ | |
34 | ||
35 | #include <linux/errno.h> | |
36 | #include "clk-cpu.h" | |
37 | ||
38 | #define E4210_SRC_CPU 0x0 | |
39 | #define E4210_STAT_CPU 0x200 | |
40 | #define E4210_DIV_CPU0 0x300 | |
41 | #define E4210_DIV_CPU1 0x304 | |
42 | #define E4210_DIV_STAT_CPU0 0x400 | |
43 | #define E4210_DIV_STAT_CPU1 0x404 | |
44 | ||
45 | #define E4210_DIV0_RATIO0_MASK 0x7 | |
46 | #define E4210_DIV1_HPM_MASK (0x7 << 4) | |
47 | #define E4210_DIV1_COPY_MASK (0x7 << 0) | |
48 | #define E4210_MUX_HPM_MASK (1 << 20) | |
49 | #define E4210_DIV0_ATB_SHIFT 16 | |
50 | #define E4210_DIV0_ATB_MASK (DIV_MASK << E4210_DIV0_ATB_SHIFT) | |
51 | ||
52 | #define MAX_DIV 8 | |
53 | #define DIV_MASK 7 | |
54 | #define DIV_MASK_ALL 0xffffffff | |
55 | #define MUX_MASK 7 | |
56 | ||
57 | /* | |
58 | * Helper function to wait until divider(s) have stabilized after the divider | |
59 | * value has changed. | |
60 | */ | |
61 | static void wait_until_divider_stable(void __iomem *div_reg, unsigned long mask) | |
62 | { | |
63 | unsigned long timeout = jiffies + msecs_to_jiffies(10); | |
64 | ||
65 | do { | |
66 | if (!(readl(div_reg) & mask)) | |
67 | return; | |
68 | } while (time_before(jiffies, timeout)); | |
69 | ||
70 | if (!(readl(div_reg) & mask)) | |
71 | return; | |
72 | ||
73 | pr_err("%s: timeout in divider stablization\n", __func__); | |
74 | } | |
75 | ||
76 | /* | |
77 | * Helper function to wait until mux has stabilized after the mux selection | |
78 | * value was changed. | |
79 | */ | |
80 | static void wait_until_mux_stable(void __iomem *mux_reg, u32 mux_pos, | |
81 | unsigned long mux_value) | |
82 | { | |
83 | unsigned long timeout = jiffies + msecs_to_jiffies(10); | |
84 | ||
85 | do { | |
86 | if (((readl(mux_reg) >> mux_pos) & MUX_MASK) == mux_value) | |
87 | return; | |
88 | } while (time_before(jiffies, timeout)); | |
89 | ||
90 | if (((readl(mux_reg) >> mux_pos) & MUX_MASK) == mux_value) | |
91 | return; | |
92 | ||
93 | pr_err("%s: re-parenting mux timed-out\n", __func__); | |
94 | } | |
95 | ||
96 | /* common round rate callback useable for all types of CPU clocks */ | |
97 | static long exynos_cpuclk_round_rate(struct clk_hw *hw, | |
98 | unsigned long drate, unsigned long *prate) | |
99 | { | |
100 | struct clk *parent = __clk_get_parent(hw->clk); | |
101 | *prate = __clk_round_rate(parent, drate); | |
102 | return *prate; | |
103 | } | |
104 | ||
105 | /* common recalc rate callback useable for all types of CPU clocks */ | |
106 | static unsigned long exynos_cpuclk_recalc_rate(struct clk_hw *hw, | |
107 | unsigned long parent_rate) | |
108 | { | |
109 | /* | |
110 | * The CPU clock output (armclk) rate is the same as its parent | |
111 | * rate. Although there exist certain dividers inside the CPU | |
112 | * clock block that could be used to divide the parent clock, | |
113 | * the driver does not make use of them currently, except during | |
114 | * frequency transitions. | |
115 | */ | |
116 | return parent_rate; | |
117 | } | |
118 | ||
119 | static const struct clk_ops exynos_cpuclk_clk_ops = { | |
120 | .recalc_rate = exynos_cpuclk_recalc_rate, | |
121 | .round_rate = exynos_cpuclk_round_rate, | |
122 | }; | |
123 | ||
124 | /* | |
125 | * Helper function to set the 'safe' dividers for the CPU clock. The parameters | |
126 | * div and mask contain the divider value and the register bit mask of the | |
127 | * dividers to be programmed. | |
128 | */ | |
129 | static void exynos_set_safe_div(void __iomem *base, unsigned long div, | |
130 | unsigned long mask) | |
131 | { | |
132 | unsigned long div0; | |
133 | ||
134 | div0 = readl(base + E4210_DIV_CPU0); | |
135 | div0 = (div0 & ~mask) | (div & mask); | |
136 | writel(div0, base + E4210_DIV_CPU0); | |
137 | wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, mask); | |
138 | } | |
139 | ||
140 | /* handler for pre-rate change notification from parent clock */ | |
141 | static int exynos_cpuclk_pre_rate_change(struct clk_notifier_data *ndata, | |
142 | struct exynos_cpuclk *cpuclk, void __iomem *base) | |
143 | { | |
144 | const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg; | |
145 | unsigned long alt_prate = clk_get_rate(cpuclk->alt_parent); | |
146 | unsigned long alt_div = 0, alt_div_mask = DIV_MASK; | |
147 | unsigned long div0, div1 = 0, mux_reg; | |
148 | ||
149 | /* find out the divider values to use for clock data */ | |
150 | while ((cfg_data->prate * 1000) != ndata->new_rate) { | |
151 | if (cfg_data->prate == 0) | |
152 | return -EINVAL; | |
153 | cfg_data++; | |
154 | } | |
155 | ||
156 | spin_lock(cpuclk->lock); | |
157 | ||
158 | /* | |
159 | * For the selected PLL clock frequency, get the pre-defined divider | |
160 | * values. If the clock for sclk_hpm is not sourced from apll, then | |
161 | * the values for DIV_COPY and DIV_HPM dividers need not be set. | |
162 | */ | |
163 | div0 = cfg_data->div0; | |
164 | if (test_bit(CLK_CPU_HAS_DIV1, &cpuclk->flags)) { | |
165 | div1 = cfg_data->div1; | |
166 | if (readl(base + E4210_SRC_CPU) & E4210_MUX_HPM_MASK) | |
167 | div1 = readl(base + E4210_DIV_CPU1) & | |
168 | (E4210_DIV1_HPM_MASK | E4210_DIV1_COPY_MASK); | |
169 | } | |
170 | ||
171 | /* | |
172 | * If the old parent clock speed is less than the clock speed of | |
173 | * the alternate parent, then it should be ensured that at no point | |
174 | * the armclk speed is more than the old_prate until the dividers are | |
175 | * set. Also workaround the issue of the dividers being set to lower | |
176 | * values before the parent clock speed is set to new lower speed | |
177 | * (this can result in too high speed of armclk output clocks). | |
178 | */ | |
179 | if (alt_prate > ndata->old_rate || ndata->old_rate > ndata->new_rate) { | |
180 | unsigned long tmp_rate = min(ndata->old_rate, ndata->new_rate); | |
181 | ||
182 | alt_div = DIV_ROUND_UP(alt_prate, tmp_rate) - 1; | |
183 | WARN_ON(alt_div >= MAX_DIV); | |
184 | ||
185 | if (test_bit(CLK_CPU_NEEDS_DEBUG_ALT_DIV, &cpuclk->flags)) { | |
186 | /* | |
187 | * In Exynos4210, ATB clock parent is also mout_core. So | |
188 | * ATB clock also needs to be mantained at safe speed. | |
189 | */ | |
190 | alt_div |= E4210_DIV0_ATB_MASK; | |
191 | alt_div_mask |= E4210_DIV0_ATB_MASK; | |
192 | } | |
193 | exynos_set_safe_div(base, alt_div, alt_div_mask); | |
194 | div0 |= alt_div; | |
195 | } | |
196 | ||
197 | /* select sclk_mpll as the alternate parent */ | |
198 | mux_reg = readl(base + E4210_SRC_CPU); | |
199 | writel(mux_reg | (1 << 16), base + E4210_SRC_CPU); | |
200 | wait_until_mux_stable(base + E4210_STAT_CPU, 16, 2); | |
201 | ||
202 | /* alternate parent is active now. set the dividers */ | |
203 | writel(div0, base + E4210_DIV_CPU0); | |
204 | wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, DIV_MASK_ALL); | |
205 | ||
206 | if (test_bit(CLK_CPU_HAS_DIV1, &cpuclk->flags)) { | |
207 | writel(div1, base + E4210_DIV_CPU1); | |
208 | wait_until_divider_stable(base + E4210_DIV_STAT_CPU1, | |
209 | DIV_MASK_ALL); | |
210 | } | |
211 | ||
212 | spin_unlock(cpuclk->lock); | |
213 | return 0; | |
214 | } | |
215 | ||
216 | /* handler for post-rate change notification from parent clock */ | |
217 | static int exynos_cpuclk_post_rate_change(struct clk_notifier_data *ndata, | |
218 | struct exynos_cpuclk *cpuclk, void __iomem *base) | |
219 | { | |
220 | const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg; | |
221 | unsigned long div = 0, div_mask = DIV_MASK; | |
222 | unsigned long mux_reg; | |
223 | ||
224 | /* find out the divider values to use for clock data */ | |
225 | if (test_bit(CLK_CPU_NEEDS_DEBUG_ALT_DIV, &cpuclk->flags)) { | |
226 | while ((cfg_data->prate * 1000) != ndata->new_rate) { | |
227 | if (cfg_data->prate == 0) | |
228 | return -EINVAL; | |
229 | cfg_data++; | |
230 | } | |
231 | } | |
232 | ||
233 | spin_lock(cpuclk->lock); | |
234 | ||
235 | /* select mout_apll as the alternate parent */ | |
236 | mux_reg = readl(base + E4210_SRC_CPU); | |
237 | writel(mux_reg & ~(1 << 16), base + E4210_SRC_CPU); | |
238 | wait_until_mux_stable(base + E4210_STAT_CPU, 16, 1); | |
239 | ||
240 | if (test_bit(CLK_CPU_NEEDS_DEBUG_ALT_DIV, &cpuclk->flags)) { | |
241 | div |= (cfg_data->div0 & E4210_DIV0_ATB_MASK); | |
242 | div_mask |= E4210_DIV0_ATB_MASK; | |
243 | } | |
244 | ||
245 | exynos_set_safe_div(base, div, div_mask); | |
246 | spin_unlock(cpuclk->lock); | |
247 | return 0; | |
248 | } | |
249 | ||
250 | /* | |
251 | * This notifier function is called for the pre-rate and post-rate change | |
252 | * notifications of the parent clock of cpuclk. | |
253 | */ | |
254 | static int exynos_cpuclk_notifier_cb(struct notifier_block *nb, | |
255 | unsigned long event, void *data) | |
256 | { | |
257 | struct clk_notifier_data *ndata = data; | |
258 | struct exynos_cpuclk *cpuclk; | |
259 | void __iomem *base; | |
260 | int err = 0; | |
261 | ||
262 | cpuclk = container_of(nb, struct exynos_cpuclk, clk_nb); | |
263 | base = cpuclk->ctrl_base; | |
264 | ||
265 | if (event == PRE_RATE_CHANGE) | |
266 | err = exynos_cpuclk_pre_rate_change(ndata, cpuclk, base); | |
267 | else if (event == POST_RATE_CHANGE) | |
268 | err = exynos_cpuclk_post_rate_change(ndata, cpuclk, base); | |
269 | ||
270 | return notifier_from_errno(err); | |
271 | } | |
272 | ||
273 | /* helper function to register a CPU clock */ | |
274 | int __init exynos_register_cpu_clock(struct samsung_clk_provider *ctx, | |
275 | unsigned int lookup_id, const char *name, const char *parent, | |
276 | const char *alt_parent, unsigned long offset, | |
277 | const struct exynos_cpuclk_cfg_data *cfg, | |
278 | unsigned long num_cfgs, unsigned long flags) | |
279 | { | |
280 | struct exynos_cpuclk *cpuclk; | |
281 | struct clk_init_data init; | |
282 | struct clk *clk; | |
283 | int ret = 0; | |
284 | ||
285 | cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL); | |
286 | if (!cpuclk) | |
287 | return -ENOMEM; | |
288 | ||
289 | init.name = name; | |
290 | init.flags = CLK_SET_RATE_PARENT; | |
291 | init.parent_names = &parent; | |
292 | init.num_parents = 1; | |
293 | init.ops = &exynos_cpuclk_clk_ops; | |
294 | ||
295 | cpuclk->hw.init = &init; | |
296 | cpuclk->ctrl_base = ctx->reg_base + offset; | |
297 | cpuclk->lock = &ctx->lock; | |
298 | cpuclk->flags = flags; | |
299 | cpuclk->clk_nb.notifier_call = exynos_cpuclk_notifier_cb; | |
300 | ||
301 | cpuclk->alt_parent = __clk_lookup(alt_parent); | |
302 | if (!cpuclk->alt_parent) { | |
303 | pr_err("%s: could not lookup alternate parent %s\n", | |
304 | __func__, alt_parent); | |
305 | ret = -EINVAL; | |
306 | goto free_cpuclk; | |
307 | } | |
308 | ||
309 | clk = __clk_lookup(parent); | |
310 | if (!clk) { | |
311 | pr_err("%s: could not lookup parent clock %s\n", | |
312 | __func__, parent); | |
313 | ret = -EINVAL; | |
314 | goto free_cpuclk; | |
315 | } | |
316 | ||
317 | ret = clk_notifier_register(clk, &cpuclk->clk_nb); | |
318 | if (ret) { | |
319 | pr_err("%s: failed to register clock notifier for %s\n", | |
320 | __func__, name); | |
321 | goto free_cpuclk; | |
322 | } | |
323 | ||
324 | cpuclk->cfg = kmemdup(cfg, sizeof(*cfg) * num_cfgs, GFP_KERNEL); | |
325 | if (!cpuclk->cfg) { | |
326 | pr_err("%s: could not allocate memory for cpuclk data\n", | |
327 | __func__); | |
328 | ret = -ENOMEM; | |
329 | goto unregister_clk_nb; | |
330 | } | |
331 | ||
332 | clk = clk_register(NULL, &cpuclk->hw); | |
333 | if (IS_ERR(clk)) { | |
334 | pr_err("%s: could not register cpuclk %s\n", __func__, name); | |
335 | ret = PTR_ERR(clk); | |
336 | goto free_cpuclk_data; | |
337 | } | |
338 | ||
339 | samsung_clk_add_lookup(ctx, clk, lookup_id); | |
340 | return 0; | |
341 | ||
342 | free_cpuclk_data: | |
343 | kfree(cpuclk->cfg); | |
344 | unregister_clk_nb: | |
345 | clk_notifier_unregister(__clk_lookup(parent), &cpuclk->clk_nb); | |
346 | free_cpuclk: | |
347 | kfree(cpuclk); | |
348 | return ret; | |
349 | } |