1 // SPDX-License-Identifier: GPL-2.0
3 * Zynq UltraScale+ MPSoC Divider support
5 * Copyright (C) 2016-2018 Xilinx
7 * Adjustable divider clock implementation
10 #include <linux/clk.h>
11 #include <linux/clk-provider.h>
12 #include <linux/slab.h>
13 #include "clk-zynqmp.h"
16 * DOC: basic adjustable divider clock that cannot gate
18 * Traits of this clock:
19 * prepare - clk_prepare only ensures that parents are prepared
20 * enable - clk_enable only ensures that parents are enabled
21 * rate - rate is adjustable. clk->rate = ceiling(parent->rate / divisor)
22 * parent - fixed parent. No clk_set_parent support
25 #define to_zynqmp_clk_divider(_hw) \
26 container_of(_hw, struct zynqmp_clk_divider, hw)
28 #define CLK_FRAC BIT(8) /* has a fractional parent */
31 * struct zynqmp_clk_divider - adjustable divider clock
32 * @hw: handle between common and hardware-specific interfaces
33 * @flags: Hardware specific flags
34 * @clk_id: Id of clock
35 * @div_type: divisor type (TYPE_DIV1 or TYPE_DIV2)
36 * @max_div: Maximum supported divisor
38 struct zynqmp_clk_divider {
46 static inline int zynqmp_divider_get_val(unsigned long parent_rate,
49 return DIV_ROUND_CLOSEST(parent_rate, rate);
53 * zynqmp_clk_divider_recalc_rate() - Recalc rate of divider clock
54 * @hw: handle between common and hardware-specific interfaces
55 * @parent_rate: rate of parent clock
57 * Return: 0 on success else error+reason
59 static unsigned long zynqmp_clk_divider_recalc_rate(struct clk_hw *hw,
60 unsigned long parent_rate)
62 struct zynqmp_clk_divider *divider = to_zynqmp_clk_divider(hw);
63 const char *clk_name = clk_hw_get_name(hw);
64 u32 clk_id = divider->clk_id;
65 u32 div_type = divider->div_type;
68 const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
70 ret = eemi_ops->clock_getdivider(clk_id, &div);
73 pr_warn_once("%s() get divider failed for %s, ret = %d\n",
74 __func__, clk_name, ret);
76 if (div_type == TYPE_DIV1)
82 WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
83 "%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
88 return DIV_ROUND_UP_ULL(parent_rate, value);
91 static void zynqmp_compute_divider(struct clk_hw *hw,
93 unsigned long parent_rate,
99 long error = LONG_MAX;
100 struct clk_hw *parent_hw = clk_hw_get_parent(hw);
101 struct zynqmp_clk_divider *pdivider = to_zynqmp_clk_divider(parent_hw);
107 for (div1 = 1; div1 <= pdivider->max_div; div1++) {
108 for (div2 = 1; div2 <= max_div; div2++) {
109 long new_error = ((parent_rate / div1) / div2) - rate;
111 if (abs(new_error) < abs(error)) {
120 * zynqmp_clk_divider_round_rate() - Round rate of divider clock
121 * @hw: handle between common and hardware-specific interfaces
122 * @rate: rate of clock to be set
123 * @prate: rate of parent clock
125 * Return: 0 on success else error+reason
127 static long zynqmp_clk_divider_round_rate(struct clk_hw *hw,
129 unsigned long *prate)
131 struct zynqmp_clk_divider *divider = to_zynqmp_clk_divider(hw);
132 const char *clk_name = clk_hw_get_name(hw);
133 u32 clk_id = divider->clk_id;
134 u32 div_type = divider->div_type;
137 const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
139 /* if read only, just return current value */
140 if (divider->flags & CLK_DIVIDER_READ_ONLY) {
141 ret = eemi_ops->clock_getdivider(clk_id, &bestdiv);
144 pr_warn_once("%s() get divider failed for %s, ret = %d\n",
145 __func__, clk_name, ret);
146 if (div_type == TYPE_DIV1)
147 bestdiv = bestdiv & 0xFFFF;
149 bestdiv = bestdiv >> 16;
151 return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
154 bestdiv = zynqmp_divider_get_val(*prate, rate);
157 * In case of two divisors, compute best divider values and return
158 * divider2 value based on compute value. div1 will be automatically
159 * set to optimum based on required total divider value.
161 if (bestdiv > divider->max_div && div_type == TYPE_DIV2 &&
162 (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
163 zynqmp_compute_divider(hw, rate, *prate,
164 divider->max_div, &bestdiv);
167 if ((clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) &&
168 (divider->flags & CLK_FRAC))
169 bestdiv = rate % *prate ? 1 : bestdiv;
170 *prate = rate * bestdiv;
176 * zynqmp_clk_divider_set_rate() - Set rate of divider clock
177 * @hw: handle between common and hardware-specific interfaces
178 * @rate: rate of clock to be set
179 * @parent_rate: rate of parent clock
181 * Return: 0 on success else error+reason
183 static int zynqmp_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
184 unsigned long parent_rate)
186 struct zynqmp_clk_divider *divider = to_zynqmp_clk_divider(hw);
187 const char *clk_name = clk_hw_get_name(hw);
188 u32 clk_id = divider->clk_id;
189 u32 div_type = divider->div_type;
192 const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
194 value = zynqmp_divider_get_val(parent_rate, rate);
195 if (div_type == TYPE_DIV1) {
196 div = value & 0xFFFF;
203 ret = eemi_ops->clock_setdivider(clk_id, div);
206 pr_warn_once("%s() set divider failed for %s, ret = %d\n",
207 __func__, clk_name, ret);
212 static const struct clk_ops zynqmp_clk_divider_ops = {
213 .recalc_rate = zynqmp_clk_divider_recalc_rate,
214 .round_rate = zynqmp_clk_divider_round_rate,
215 .set_rate = zynqmp_clk_divider_set_rate,
219 * zynqmp_clk_register_divider() - Register a divider clock
220 * @name: Name of this clock
221 * @clk_id: Id of clock
222 * @parents: Name of this clock's parents
223 * @num_parents: Number of parents
224 * @nodes: Clock topology node
226 * Return: clock hardware to registered clock divider
228 struct clk_hw *zynqmp_clk_register_divider(const char *name,
230 const char * const *parents,
232 const struct clock_topology *nodes)
234 struct zynqmp_clk_divider *div;
236 struct clk_init_data init;
238 const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
239 struct zynqmp_pm_query_data qdata = {0};
240 u32 ret_payload[PAYLOAD_ARG_CNT];
242 /* allocate the divider */
243 div = kzalloc(sizeof(*div), GFP_KERNEL);
245 return ERR_PTR(-ENOMEM);
248 init.ops = &zynqmp_clk_divider_ops;
249 init.flags = nodes->flag;
250 init.parent_names = parents;
251 init.num_parents = 1;
253 /* struct clk_divider assignments */
254 div->flags = nodes->type_flag;
255 div->hw.init = &init;
256 div->clk_id = clk_id;
257 div->div_type = nodes->type;
260 * To achieve best possible rate, maximum limit of divider is required
261 * while computation. Get maximum supported divisor from firmware. To
262 * maintain backward compatibility assign maximum possible value(0xFFFF)
263 * if query for max divisor is not successful.
265 qdata.qid = PM_QID_CLOCK_GET_MAX_DIVISOR;
267 qdata.arg2 = nodes->type;
268 ret = eemi_ops->query_data(qdata, ret_payload);
270 div->max_div = 0XFFFF;
272 div->max_div = ret_payload[1];
275 ret = clk_hw_register(NULL, hw);
283 EXPORT_SYMBOL_GPL(zynqmp_clk_register_divider);