1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * System Control and Power Interface (SCMI) Protocol based clock driver 4 * 5 * Copyright (C) 2018-2021 ARM Ltd. 6 */ 7 8 #include <linux/clk-provider.h> 9 #include <linux/device.h> 10 #include <linux/err.h> 11 #include <linux/of.h> 12 #include <linux/module.h> 13 #include <linux/scmi_protocol.h> 14 #include <asm/div64.h> 15 16 static const struct scmi_clk_proto_ops *scmi_proto_clk_ops; 17 18 struct scmi_clk { 19 u32 id; 20 struct clk_hw hw; 21 const struct scmi_clock_info *info; 22 const struct scmi_protocol_handle *ph; 23 }; 24 25 #define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw) 26 27 static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw, 28 unsigned long parent_rate) 29 { 30 int ret; 31 u64 rate; 32 struct scmi_clk *clk = to_scmi_clk(hw); 33 34 ret = scmi_proto_clk_ops->rate_get(clk->ph, clk->id, &rate); 35 if (ret) 36 return 0; 37 return rate; 38 } 39 40 static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate, 41 unsigned long *parent_rate) 42 { 43 u64 fmin, fmax, ftmp; 44 struct scmi_clk *clk = to_scmi_clk(hw); 45 46 /* 47 * We can't figure out what rate it will be, so just return the 48 * rate back to the caller. scmi_clk_recalc_rate() will be called 49 * after the rate is set and we'll know what rate the clock is 50 * running at then. 51 */ 52 if (clk->info->rate_discrete) 53 return rate; 54 55 fmin = clk->info->range.min_rate; 56 fmax = clk->info->range.max_rate; 57 if (rate <= fmin) 58 return fmin; 59 else if (rate >= fmax) 60 return fmax; 61 62 ftmp = rate - fmin; 63 ftmp += clk->info->range.step_size - 1; /* to round up */ 64 do_div(ftmp, clk->info->range.step_size); 65 66 return ftmp * clk->info->range.step_size + fmin; 67 } 68 69 static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate, 70 unsigned long parent_rate) 71 { 72 struct scmi_clk *clk = to_scmi_clk(hw); 73 74 return scmi_proto_clk_ops->rate_set(clk->ph, clk->id, rate); 75 } 76 77 static int scmi_clk_enable(struct clk_hw *hw) 78 { 79 struct scmi_clk *clk = to_scmi_clk(hw); 80 81 return scmi_proto_clk_ops->enable(clk->ph, clk->id); 82 } 83 84 static void scmi_clk_disable(struct clk_hw *hw) 85 { 86 struct scmi_clk *clk = to_scmi_clk(hw); 87 88 scmi_proto_clk_ops->disable(clk->ph, clk->id); 89 } 90 91 static const struct clk_ops scmi_clk_ops = { 92 .recalc_rate = scmi_clk_recalc_rate, 93 .round_rate = scmi_clk_round_rate, 94 .set_rate = scmi_clk_set_rate, 95 /* 96 * We can't provide enable/disable callback as we can't perform the same 97 * in atomic context. Since the clock framework provides standard API 98 * clk_prepare_enable that helps cases using clk_enable in non-atomic 99 * context, it should be fine providing prepare/unprepare. 100 */ 101 .prepare = scmi_clk_enable, 102 .unprepare = scmi_clk_disable, 103 }; 104 105 static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk) 106 { 107 int ret; 108 unsigned long min_rate, max_rate; 109 110 struct clk_init_data init = { 111 .flags = CLK_GET_RATE_NOCACHE, 112 .num_parents = 0, 113 .ops = &scmi_clk_ops, 114 .name = sclk->info->name, 115 }; 116 117 sclk->hw.init = &init; 118 ret = devm_clk_hw_register(dev, &sclk->hw); 119 if (ret) 120 return ret; 121 122 if (sclk->info->rate_discrete) { 123 int num_rates = sclk->info->list.num_rates; 124 125 if (num_rates <= 0) 126 return -EINVAL; 127 128 min_rate = sclk->info->list.rates[0]; 129 max_rate = sclk->info->list.rates[num_rates - 1]; 130 } else { 131 min_rate = sclk->info->range.min_rate; 132 max_rate = sclk->info->range.max_rate; 133 } 134 135 clk_hw_set_rate_range(&sclk->hw, min_rate, max_rate); 136 return ret; 137 } 138 139 static int scmi_clocks_probe(struct scmi_device *sdev) 140 { 141 int idx, count, err; 142 struct clk_hw **hws; 143 struct clk_hw_onecell_data *clk_data; 144 struct device *dev = &sdev->dev; 145 struct device_node *np = dev->of_node; 146 const struct scmi_handle *handle = sdev->handle; 147 struct scmi_protocol_handle *ph; 148 149 if (!handle) 150 return -ENODEV; 151 152 scmi_proto_clk_ops = 153 handle->devm_protocol_get(sdev, SCMI_PROTOCOL_CLOCK, &ph); 154 if (IS_ERR(scmi_proto_clk_ops)) 155 return PTR_ERR(scmi_proto_clk_ops); 156 157 count = scmi_proto_clk_ops->count_get(ph); 158 if (count < 0) { 159 dev_err(dev, "%pOFn: invalid clock output count\n", np); 160 return -EINVAL; 161 } 162 163 clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, count), 164 GFP_KERNEL); 165 if (!clk_data) 166 return -ENOMEM; 167 168 clk_data->num = count; 169 hws = clk_data->hws; 170 171 for (idx = 0; idx < count; idx++) { 172 struct scmi_clk *sclk; 173 174 sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL); 175 if (!sclk) 176 return -ENOMEM; 177 178 sclk->info = scmi_proto_clk_ops->info_get(ph, idx); 179 if (!sclk->info) { 180 dev_dbg(dev, "invalid clock info for idx %d\n", idx); 181 continue; 182 } 183 184 sclk->id = idx; 185 sclk->ph = ph; 186 187 err = scmi_clk_ops_init(dev, sclk); 188 if (err) { 189 dev_err(dev, "failed to register clock %d\n", idx); 190 devm_kfree(dev, sclk); 191 hws[idx] = NULL; 192 } else { 193 dev_dbg(dev, "Registered clock:%s\n", sclk->info->name); 194 hws[idx] = &sclk->hw; 195 } 196 } 197 198 return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, 199 clk_data); 200 } 201 202 static const struct scmi_device_id scmi_id_table[] = { 203 { SCMI_PROTOCOL_CLOCK, "clocks" }, 204 { }, 205 }; 206 MODULE_DEVICE_TABLE(scmi, scmi_id_table); 207 208 static struct scmi_driver scmi_clocks_driver = { 209 .name = "scmi-clocks", 210 .probe = scmi_clocks_probe, 211 .id_table = scmi_id_table, 212 }; 213 module_scmi_driver(scmi_clocks_driver); 214 215 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 216 MODULE_DESCRIPTION("ARM SCMI clock driver"); 217 MODULE_LICENSE("GPL v2"); 218