1 /*
2  * Copyright (C) 2014 Broadcom Corporation
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation version 2.
7  *
8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9  * kind, whether express or implied; without even the implied warranty
10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/err.h>
17 #include <linux/clk-provider.h>
18 #include <linux/io.h>
19 #include <linux/of.h>
20 #include <linux/clkdev.h>
21 #include <linux/of_address.h>
22 
23 #include "clk-iproc.h"
24 
25 #define IPROC_CLK_MAX_FREQ_POLICY                    0x3
26 #define IPROC_CLK_POLICY_FREQ_OFFSET                 0x008
27 #define IPROC_CLK_POLICY_FREQ_POLICY_FREQ_SHIFT      8
28 #define IPROC_CLK_POLICY_FREQ_POLICY_FREQ_MASK       0x7
29 
30 #define IPROC_CLK_PLLARMA_OFFSET                     0xc00
31 #define IPROC_CLK_PLLARMA_LOCK_SHIFT                 28
32 #define IPROC_CLK_PLLARMA_PDIV_SHIFT                 24
33 #define IPROC_CLK_PLLARMA_PDIV_MASK                  0xf
34 #define IPROC_CLK_PLLARMA_NDIV_INT_SHIFT             8
35 #define IPROC_CLK_PLLARMA_NDIV_INT_MASK              0x3ff
36 
37 #define IPROC_CLK_PLLARMB_OFFSET                     0xc04
38 #define IPROC_CLK_PLLARMB_NDIV_FRAC_MASK             0xfffff
39 
40 #define IPROC_CLK_PLLARMC_OFFSET                     0xc08
41 #define IPROC_CLK_PLLARMC_BYPCLK_EN_SHIFT            8
42 #define IPROC_CLK_PLLARMC_MDIV_MASK                  0xff
43 
44 #define IPROC_CLK_PLLARMCTL5_OFFSET                  0xc20
45 #define IPROC_CLK_PLLARMCTL5_H_MDIV_MASK             0xff
46 
47 #define IPROC_CLK_PLLARM_OFFSET_OFFSET               0xc24
48 #define IPROC_CLK_PLLARM_SW_CTL_SHIFT                29
49 #define IPROC_CLK_PLLARM_NDIV_INT_OFFSET_SHIFT       20
50 #define IPROC_CLK_PLLARM_NDIV_INT_OFFSET_MASK        0xff
51 #define IPROC_CLK_PLLARM_NDIV_FRAC_OFFSET_MASK       0xfffff
52 
53 #define IPROC_CLK_ARM_DIV_OFFSET                     0xe00
54 #define IPROC_CLK_ARM_DIV_PLL_SELECT_OVERRIDE_SHIFT  4
55 #define IPROC_CLK_ARM_DIV_ARM_PLL_SELECT_MASK        0xf
56 
57 #define IPROC_CLK_POLICY_DBG_OFFSET                  0xec0
58 #define IPROC_CLK_POLICY_DBG_ACT_FREQ_SHIFT          12
59 #define IPROC_CLK_POLICY_DBG_ACT_FREQ_MASK           0x7
60 
61 enum iproc_arm_pll_fid {
62 	ARM_PLL_FID_CRYSTAL_CLK   = 0,
63 	ARM_PLL_FID_SYS_CLK       = 2,
64 	ARM_PLL_FID_CH0_SLOW_CLK  = 6,
65 	ARM_PLL_FID_CH1_FAST_CLK  = 7
66 };
67 
68 struct iproc_arm_pll {
69 	struct clk_hw hw;
70 	void __iomem *base;
71 	unsigned long rate;
72 };
73 
74 #define to_iproc_arm_pll(hw) container_of(hw, struct iproc_arm_pll, hw)
75 
__get_fid(struct iproc_arm_pll * pll)76 static unsigned int __get_fid(struct iproc_arm_pll *pll)
77 {
78 	u32 val;
79 	unsigned int policy, fid, active_fid;
80 
81 	val = readl(pll->base + IPROC_CLK_ARM_DIV_OFFSET);
82 	if (val & (1 << IPROC_CLK_ARM_DIV_PLL_SELECT_OVERRIDE_SHIFT))
83 		policy = val & IPROC_CLK_ARM_DIV_ARM_PLL_SELECT_MASK;
84 	else
85 		policy = 0;
86 
87 	/* something is seriously wrong */
88 	BUG_ON(policy > IPROC_CLK_MAX_FREQ_POLICY);
89 
90 	val = readl(pll->base + IPROC_CLK_POLICY_FREQ_OFFSET);
91 	fid = (val >> (IPROC_CLK_POLICY_FREQ_POLICY_FREQ_SHIFT * policy)) &
92 		IPROC_CLK_POLICY_FREQ_POLICY_FREQ_MASK;
93 
94 	val = readl(pll->base + IPROC_CLK_POLICY_DBG_OFFSET);
95 	active_fid = IPROC_CLK_POLICY_DBG_ACT_FREQ_MASK &
96 		(val >> IPROC_CLK_POLICY_DBG_ACT_FREQ_SHIFT);
97 	if (fid != active_fid) {
98 		pr_debug("%s: fid override %u->%u\n", __func__,	fid,
99 				active_fid);
100 		fid = active_fid;
101 	}
102 
103 	pr_debug("%s: active fid: %u\n", __func__, fid);
104 
105 	return fid;
106 }
107 
108 /*
109  * Determine the mdiv (post divider) based on the frequency ID being used.
110  * There are 4 sources that can be used to derive the output clock rate:
111  *    - 25 MHz Crystal
112  *    - System clock
113  *    - PLL channel 0 (slow clock)
114  *    - PLL channel 1 (fast clock)
115  */
__get_mdiv(struct iproc_arm_pll * pll)116 static int __get_mdiv(struct iproc_arm_pll *pll)
117 {
118 	unsigned int fid;
119 	int mdiv;
120 	u32 val;
121 
122 	fid = __get_fid(pll);
123 
124 	switch (fid) {
125 	case ARM_PLL_FID_CRYSTAL_CLK:
126 	case ARM_PLL_FID_SYS_CLK:
127 		mdiv = 1;
128 		break;
129 
130 	case ARM_PLL_FID_CH0_SLOW_CLK:
131 		val = readl(pll->base + IPROC_CLK_PLLARMC_OFFSET);
132 		mdiv = val & IPROC_CLK_PLLARMC_MDIV_MASK;
133 		if (mdiv == 0)
134 			mdiv = 256;
135 		break;
136 
137 	case ARM_PLL_FID_CH1_FAST_CLK:
138 		val = readl(pll->base +	IPROC_CLK_PLLARMCTL5_OFFSET);
139 		mdiv = val & IPROC_CLK_PLLARMCTL5_H_MDIV_MASK;
140 		if (mdiv == 0)
141 			mdiv = 256;
142 		break;
143 
144 	default:
145 		mdiv = -EFAULT;
146 	}
147 
148 	return mdiv;
149 }
150 
__get_ndiv(struct iproc_arm_pll * pll)151 static unsigned int __get_ndiv(struct iproc_arm_pll *pll)
152 {
153 	u32 val;
154 	unsigned int ndiv_int, ndiv_frac, ndiv;
155 
156 	val = readl(pll->base + IPROC_CLK_PLLARM_OFFSET_OFFSET);
157 	if (val & (1 << IPROC_CLK_PLLARM_SW_CTL_SHIFT)) {
158 		/*
159 		 * offset mode is active. Read the ndiv from the PLLARM OFFSET
160 		 * register
161 		 */
162 		ndiv_int = (val >> IPROC_CLK_PLLARM_NDIV_INT_OFFSET_SHIFT) &
163 			IPROC_CLK_PLLARM_NDIV_INT_OFFSET_MASK;
164 		if (ndiv_int == 0)
165 			ndiv_int = 256;
166 
167 		ndiv_frac = val & IPROC_CLK_PLLARM_NDIV_FRAC_OFFSET_MASK;
168 	} else {
169 		/* offset mode not active */
170 		val = readl(pll->base + IPROC_CLK_PLLARMA_OFFSET);
171 		ndiv_int = (val >> IPROC_CLK_PLLARMA_NDIV_INT_SHIFT) &
172 			IPROC_CLK_PLLARMA_NDIV_INT_MASK;
173 		if (ndiv_int == 0)
174 			ndiv_int = 1024;
175 
176 		val = readl(pll->base + IPROC_CLK_PLLARMB_OFFSET);
177 		ndiv_frac = val & IPROC_CLK_PLLARMB_NDIV_FRAC_MASK;
178 	}
179 
180 	ndiv = (ndiv_int << 20) | ndiv_frac;
181 
182 	return ndiv;
183 }
184 
185 /*
186  * The output frequency of the ARM PLL is calculated based on the ARM PLL
187  * divider values:
188  *   pdiv = ARM PLL pre-divider
189  *   ndiv = ARM PLL multiplier
190  *   mdiv = ARM PLL post divider
191  *
192  * The frequency is calculated by:
193  *   ((ndiv * parent clock rate) / pdiv) / mdiv
194  */
iproc_arm_pll_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)195 static unsigned long iproc_arm_pll_recalc_rate(struct clk_hw *hw,
196 		unsigned long parent_rate)
197 {
198 	struct iproc_arm_pll *pll = to_iproc_arm_pll(hw);
199 	u32 val;
200 	int mdiv;
201 	u64 ndiv;
202 	unsigned int pdiv;
203 
204 	/* in bypass mode, use parent rate */
205 	val = readl(pll->base + IPROC_CLK_PLLARMC_OFFSET);
206 	if (val & (1 << IPROC_CLK_PLLARMC_BYPCLK_EN_SHIFT)) {
207 		pll->rate = parent_rate;
208 		return pll->rate;
209 	}
210 
211 	/* PLL needs to be locked */
212 	val = readl(pll->base + IPROC_CLK_PLLARMA_OFFSET);
213 	if (!(val & (1 << IPROC_CLK_PLLARMA_LOCK_SHIFT))) {
214 		pll->rate = 0;
215 		return 0;
216 	}
217 
218 	pdiv = (val >> IPROC_CLK_PLLARMA_PDIV_SHIFT) &
219 		IPROC_CLK_PLLARMA_PDIV_MASK;
220 	if (pdiv == 0)
221 		pdiv = 16;
222 
223 	ndiv = __get_ndiv(pll);
224 	mdiv = __get_mdiv(pll);
225 	if (mdiv <= 0) {
226 		pll->rate = 0;
227 		return 0;
228 	}
229 	pll->rate = (ndiv * parent_rate) >> 20;
230 	pll->rate = (pll->rate / pdiv) / mdiv;
231 
232 	pr_debug("%s: ARM PLL rate: %lu. parent rate: %lu\n", __func__,
233 		 pll->rate, parent_rate);
234 	pr_debug("%s: ndiv_int: %u, pdiv: %u, mdiv: %d\n", __func__,
235 		 (unsigned int)(ndiv >> 20), pdiv, mdiv);
236 
237 	return pll->rate;
238 }
239 
240 static const struct clk_ops iproc_arm_pll_ops = {
241 	.recalc_rate = iproc_arm_pll_recalc_rate,
242 };
243 
iproc_armpll_setup(struct device_node * node)244 void __init iproc_armpll_setup(struct device_node *node)
245 {
246 	int ret;
247 	struct iproc_arm_pll *pll;
248 	struct clk_init_data init;
249 	const char *parent_name;
250 
251 	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
252 	if (WARN_ON(!pll))
253 		return;
254 
255 	pll->base = of_iomap(node, 0);
256 	if (WARN_ON(!pll->base))
257 		goto err_free_pll;
258 
259 	init.name = node->name;
260 	init.ops = &iproc_arm_pll_ops;
261 	init.flags = 0;
262 	parent_name = of_clk_get_parent_name(node, 0);
263 	init.parent_names = (parent_name ? &parent_name : NULL);
264 	init.num_parents = (parent_name ? 1 : 0);
265 	pll->hw.init = &init;
266 
267 	ret = clk_hw_register(NULL, &pll->hw);
268 	if (WARN_ON(ret))
269 		goto err_iounmap;
270 
271 	ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, &pll->hw);
272 	if (WARN_ON(ret))
273 		goto err_clk_unregister;
274 
275 	return;
276 
277 err_clk_unregister:
278 	clk_hw_unregister(&pll->hw);
279 err_iounmap:
280 	iounmap(pll->base);
281 err_free_pll:
282 	kfree(pll);
283 }
284