1 // SPDX-License-Identifier: GPL-2.0
5 * This driver supports the fractional plls found in the imx8m SOCs
7 * Documentation for this fractional pll can be found at:
8 * https://www.nxp.com/docs/en/reference-manual/IMX8MDQLQRM.pdf#page=834
11 #include <linux/clk-provider.h>
12 #include <linux/err.h>
13 #include <linux/iopoll.h>
14 #include <linux/slab.h>
15 #include <linux/bitfield.h>
22 #define PLL_LOCK_STATUS BIT(31)
23 #define PLL_PD_MASK BIT(19)
24 #define PLL_BYPASS_MASK BIT(14)
25 #define PLL_NEWDIV_VAL BIT(12)
26 #define PLL_NEWDIV_ACK BIT(11)
27 #define PLL_FRAC_DIV_MASK GENMASK(30, 7)
28 #define PLL_INT_DIV_MASK GENMASK(6, 0)
29 #define PLL_OUTPUT_DIV_MASK GENMASK(4, 0)
30 #define PLL_FRAC_DENOM 0x1000000
32 #define PLL_FRAC_LOCK_TIMEOUT 10000
33 #define PLL_FRAC_ACK_TIMEOUT 500000
40 #define to_clk_frac_pll(_hw) container_of(_hw, struct clk_frac_pll, hw)
42 static int clk_wait_lock(struct clk_frac_pll *pll)
46 return readl_poll_timeout(pll->base, val, val & PLL_LOCK_STATUS, 0,
47 PLL_FRAC_LOCK_TIMEOUT);
50 static int clk_wait_ack(struct clk_frac_pll *pll)
54 /* return directly if the pll is in powerdown or in bypass */
55 if (readl_relaxed(pll->base) & (PLL_PD_MASK | PLL_BYPASS_MASK))
58 /* Wait for the pll's divfi and divff to be reloaded */
59 return readl_poll_timeout(pll->base, val, val & PLL_NEWDIV_ACK, 0,
60 PLL_FRAC_ACK_TIMEOUT);
63 static int clk_pll_prepare(struct clk_hw *hw)
65 struct clk_frac_pll *pll = to_clk_frac_pll(hw);
68 val = readl_relaxed(pll->base + PLL_CFG0);
70 writel_relaxed(val, pll->base + PLL_CFG0);
72 return clk_wait_lock(pll);
75 static void clk_pll_unprepare(struct clk_hw *hw)
77 struct clk_frac_pll *pll = to_clk_frac_pll(hw);
80 val = readl_relaxed(pll->base + PLL_CFG0);
82 writel_relaxed(val, pll->base + PLL_CFG0);
85 static int clk_pll_is_prepared(struct clk_hw *hw)
87 struct clk_frac_pll *pll = to_clk_frac_pll(hw);
90 val = readl_relaxed(pll->base + PLL_CFG0);
91 return (val & PLL_PD_MASK) ? 0 : 1;
94 static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
95 unsigned long parent_rate)
97 struct clk_frac_pll *pll = to_clk_frac_pll(hw);
98 u32 val, divff, divfi, divq;
99 u64 temp64 = parent_rate;
102 val = readl_relaxed(pll->base + PLL_CFG0);
103 divq = (FIELD_GET(PLL_OUTPUT_DIV_MASK, val) + 1) * 2;
104 val = readl_relaxed(pll->base + PLL_CFG1);
105 divff = FIELD_GET(PLL_FRAC_DIV_MASK, val);
106 divfi = FIELD_GET(PLL_INT_DIV_MASK, val);
110 do_div(temp64, PLL_FRAC_DENOM);
111 do_div(temp64, divq);
113 rate = parent_rate * 8 * (divfi + 1);
120 static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
121 unsigned long *prate)
123 u64 parent_rate = *prate;
130 do_div(temp64, parent_rate);
132 temp64 = rate - divfi * parent_rate;
133 temp64 *= PLL_FRAC_DENOM;
134 do_div(temp64, parent_rate);
137 temp64 = parent_rate;
139 do_div(temp64, PLL_FRAC_DENOM);
141 rate = parent_rate * divfi + temp64;
147 * To simplify the clock calculation, we can keep the 'PLL_OUTPUT_VAL' at zero
148 * (means the PLL output will be divided by 2). So the PLL output can use
150 * pllout = parent_rate * 8 / 2 * DIVF_VAL;
151 * where DIVF_VAL = 1 + DIVFI + DIVFF / 2^24.
153 static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
154 unsigned long parent_rate)
156 struct clk_frac_pll *pll = to_clk_frac_pll(hw);
157 u32 val, divfi, divff;
163 divfi = rate / parent_rate;
164 temp64 = parent_rate * divfi;
165 temp64 = rate - temp64;
166 temp64 *= PLL_FRAC_DENOM;
167 do_div(temp64, parent_rate);
170 val = readl_relaxed(pll->base + PLL_CFG1);
171 val &= ~(PLL_FRAC_DIV_MASK | PLL_INT_DIV_MASK);
172 val |= (divff << 7) | (divfi - 1);
173 writel_relaxed(val, pll->base + PLL_CFG1);
175 val = readl_relaxed(pll->base + PLL_CFG0);
177 writel_relaxed(val, pll->base + PLL_CFG0);
179 /* Set the NEV_DIV_VAL to reload the DIVFI and DIVFF */
180 val = readl_relaxed(pll->base + PLL_CFG0);
181 val |= PLL_NEWDIV_VAL;
182 writel_relaxed(val, pll->base + PLL_CFG0);
184 ret = clk_wait_ack(pll);
186 /* clear the NEV_DIV_VAL */
187 val = readl_relaxed(pll->base + PLL_CFG0);
188 val &= ~PLL_NEWDIV_VAL;
189 writel_relaxed(val, pll->base + PLL_CFG0);
194 static const struct clk_ops clk_frac_pll_ops = {
195 .prepare = clk_pll_prepare,
196 .unprepare = clk_pll_unprepare,
197 .is_prepared = clk_pll_is_prepared,
198 .recalc_rate = clk_pll_recalc_rate,
199 .round_rate = clk_pll_round_rate,
200 .set_rate = clk_pll_set_rate,
203 struct clk *imx_clk_frac_pll(const char *name, const char *parent_name,
206 struct clk_init_data init;
207 struct clk_frac_pll *pll;
211 pll = kzalloc(sizeof(*pll), GFP_KERNEL);
213 return ERR_PTR(-ENOMEM);
216 init.ops = &clk_frac_pll_ops;
218 init.parent_names = &parent_name;
219 init.num_parents = 1;
222 pll->hw.init = &init;
226 ret = clk_hw_register(NULL, hw);