1 /* 2 * System Control and Power Interface (SCPI) Protocol based clock driver 3 * 4 * Copyright (C) 2015 ARM Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms and conditions of the GNU General Public License, 8 * version 2, as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 13 * more details. 14 * 15 * You should have received a copy of the GNU General Public License along with 16 * this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 19 #include <linux/clk-provider.h> 20 #include <linux/device.h> 21 #include <linux/err.h> 22 #include <linux/of.h> 23 #include <linux/module.h> 24 #include <linux/of_platform.h> 25 #include <linux/platform_device.h> 26 #include <linux/scpi_protocol.h> 27 28 struct scpi_clk { 29 u32 id; 30 struct clk_hw hw; 31 struct scpi_dvfs_info *info; 32 struct scpi_ops *scpi_ops; 33 }; 34 35 #define to_scpi_clk(clk) container_of(clk, struct scpi_clk, hw) 36 37 static struct platform_device *cpufreq_dev; 38 39 static unsigned long scpi_clk_recalc_rate(struct clk_hw *hw, 40 unsigned long parent_rate) 41 { 42 struct scpi_clk *clk = to_scpi_clk(hw); 43 44 return clk->scpi_ops->clk_get_val(clk->id); 45 } 46 47 static long scpi_clk_round_rate(struct clk_hw *hw, unsigned long rate, 48 unsigned long *parent_rate) 49 { 50 /* 51 * We can't figure out what rate it will be, so just return the 52 * rate back to the caller. scpi_clk_recalc_rate() will be called 53 * after the rate is set and we'll know what rate the clock is 54 * running at then. 55 */ 56 return rate; 57 } 58 59 static int scpi_clk_set_rate(struct clk_hw *hw, unsigned long rate, 60 unsigned long parent_rate) 61 { 62 struct scpi_clk *clk = to_scpi_clk(hw); 63 64 return clk->scpi_ops->clk_set_val(clk->id, rate); 65 } 66 67 static const struct clk_ops scpi_clk_ops = { 68 .recalc_rate = scpi_clk_recalc_rate, 69 .round_rate = scpi_clk_round_rate, 70 .set_rate = scpi_clk_set_rate, 71 }; 72 73 /* find closest match to given frequency in OPP table */ 74 static long __scpi_dvfs_round_rate(struct scpi_clk *clk, unsigned long rate) 75 { 76 int idx; 77 unsigned long fmin = 0, fmax = ~0, ftmp; 78 const struct scpi_opp *opp = clk->info->opps; 79 80 for (idx = 0; idx < clk->info->count; idx++, opp++) { 81 ftmp = opp->freq; 82 if (ftmp >= rate) { 83 if (ftmp <= fmax) 84 fmax = ftmp; 85 break; 86 } else if (ftmp >= fmin) { 87 fmin = ftmp; 88 } 89 } 90 return fmax != ~0 ? fmax : fmin; 91 } 92 93 static unsigned long scpi_dvfs_recalc_rate(struct clk_hw *hw, 94 unsigned long parent_rate) 95 { 96 struct scpi_clk *clk = to_scpi_clk(hw); 97 int idx = clk->scpi_ops->dvfs_get_idx(clk->id); 98 const struct scpi_opp *opp; 99 100 if (idx < 0) 101 return 0; 102 103 opp = clk->info->opps + idx; 104 return opp->freq; 105 } 106 107 static long scpi_dvfs_round_rate(struct clk_hw *hw, unsigned long rate, 108 unsigned long *parent_rate) 109 { 110 struct scpi_clk *clk = to_scpi_clk(hw); 111 112 return __scpi_dvfs_round_rate(clk, rate); 113 } 114 115 static int __scpi_find_dvfs_index(struct scpi_clk *clk, unsigned long rate) 116 { 117 int idx, max_opp = clk->info->count; 118 const struct scpi_opp *opp = clk->info->opps; 119 120 for (idx = 0; idx < max_opp; idx++, opp++) 121 if (opp->freq == rate) 122 return idx; 123 return -EINVAL; 124 } 125 126 static int scpi_dvfs_set_rate(struct clk_hw *hw, unsigned long rate, 127 unsigned long parent_rate) 128 { 129 struct scpi_clk *clk = to_scpi_clk(hw); 130 int ret = __scpi_find_dvfs_index(clk, rate); 131 132 if (ret < 0) 133 return ret; 134 return clk->scpi_ops->dvfs_set_idx(clk->id, (u8)ret); 135 } 136 137 static const struct clk_ops scpi_dvfs_ops = { 138 .recalc_rate = scpi_dvfs_recalc_rate, 139 .round_rate = scpi_dvfs_round_rate, 140 .set_rate = scpi_dvfs_set_rate, 141 }; 142 143 static const struct of_device_id scpi_clk_match[] = { 144 { .compatible = "arm,scpi-dvfs-clocks", .data = &scpi_dvfs_ops, }, 145 { .compatible = "arm,scpi-variable-clocks", .data = &scpi_clk_ops, }, 146 {} 147 }; 148 149 static int 150 scpi_clk_ops_init(struct device *dev, const struct of_device_id *match, 151 struct scpi_clk *sclk, const char *name) 152 { 153 struct clk_init_data init; 154 unsigned long min = 0, max = 0; 155 int ret; 156 157 init.name = name; 158 init.flags = 0; 159 init.num_parents = 0; 160 init.ops = match->data; 161 sclk->hw.init = &init; 162 sclk->scpi_ops = get_scpi_ops(); 163 164 if (init.ops == &scpi_dvfs_ops) { 165 sclk->info = sclk->scpi_ops->dvfs_get_info(sclk->id); 166 if (IS_ERR(sclk->info)) 167 return PTR_ERR(sclk->info); 168 } else if (init.ops == &scpi_clk_ops) { 169 if (sclk->scpi_ops->clk_get_range(sclk->id, &min, &max) || !max) 170 return -EINVAL; 171 } else { 172 return -EINVAL; 173 } 174 175 ret = devm_clk_hw_register(dev, &sclk->hw); 176 if (!ret && max) 177 clk_hw_set_rate_range(&sclk->hw, min, max); 178 return ret; 179 } 180 181 struct scpi_clk_data { 182 struct scpi_clk **clk; 183 unsigned int clk_num; 184 }; 185 186 static struct clk_hw * 187 scpi_of_clk_src_get(struct of_phandle_args *clkspec, void *data) 188 { 189 struct scpi_clk *sclk; 190 struct scpi_clk_data *clk_data = data; 191 unsigned int idx = clkspec->args[0], count; 192 193 for (count = 0; count < clk_data->clk_num; count++) { 194 sclk = clk_data->clk[count]; 195 if (idx == sclk->id) 196 return &sclk->hw; 197 } 198 199 return ERR_PTR(-EINVAL); 200 } 201 202 static int scpi_clk_add(struct device *dev, struct device_node *np, 203 const struct of_device_id *match) 204 { 205 int idx, count, err; 206 struct scpi_clk_data *clk_data; 207 208 count = of_property_count_strings(np, "clock-output-names"); 209 if (count < 0) { 210 dev_err(dev, "%s: invalid clock output count\n", np->name); 211 return -EINVAL; 212 } 213 214 clk_data = devm_kmalloc(dev, sizeof(*clk_data), GFP_KERNEL); 215 if (!clk_data) 216 return -ENOMEM; 217 218 clk_data->clk_num = count; 219 clk_data->clk = devm_kcalloc(dev, count, sizeof(*clk_data->clk), 220 GFP_KERNEL); 221 if (!clk_data->clk) 222 return -ENOMEM; 223 224 for (idx = 0; idx < count; idx++) { 225 struct scpi_clk *sclk; 226 const char *name; 227 u32 val; 228 229 sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL); 230 if (!sclk) 231 return -ENOMEM; 232 233 if (of_property_read_string_index(np, "clock-output-names", 234 idx, &name)) { 235 dev_err(dev, "invalid clock name @ %s\n", np->name); 236 return -EINVAL; 237 } 238 239 if (of_property_read_u32_index(np, "clock-indices", 240 idx, &val)) { 241 dev_err(dev, "invalid clock index @ %s\n", np->name); 242 return -EINVAL; 243 } 244 245 sclk->id = val; 246 247 err = scpi_clk_ops_init(dev, match, sclk, name); 248 if (err) { 249 dev_err(dev, "failed to register clock '%s'\n", name); 250 return err; 251 } 252 253 dev_dbg(dev, "Registered clock '%s'\n", name); 254 clk_data->clk[idx] = sclk; 255 } 256 257 return of_clk_add_hw_provider(np, scpi_of_clk_src_get, clk_data); 258 } 259 260 static int scpi_clocks_remove(struct platform_device *pdev) 261 { 262 struct device *dev = &pdev->dev; 263 struct device_node *child, *np = dev->of_node; 264 265 if (cpufreq_dev) { 266 platform_device_unregister(cpufreq_dev); 267 cpufreq_dev = NULL; 268 } 269 270 for_each_available_child_of_node(np, child) 271 of_clk_del_provider(np); 272 return 0; 273 } 274 275 static int scpi_clocks_probe(struct platform_device *pdev) 276 { 277 int ret; 278 struct device *dev = &pdev->dev; 279 struct device_node *child, *np = dev->of_node; 280 const struct of_device_id *match; 281 282 if (!get_scpi_ops()) 283 return -ENXIO; 284 285 for_each_available_child_of_node(np, child) { 286 match = of_match_node(scpi_clk_match, child); 287 if (!match) 288 continue; 289 ret = scpi_clk_add(dev, child, match); 290 if (ret) { 291 scpi_clocks_remove(pdev); 292 of_node_put(child); 293 return ret; 294 } 295 296 if (match->data != &scpi_dvfs_ops) 297 continue; 298 /* Add the virtual cpufreq device if it's DVFS clock provider */ 299 cpufreq_dev = platform_device_register_simple("scpi-cpufreq", 300 -1, NULL, 0); 301 if (IS_ERR(cpufreq_dev)) 302 pr_warn("unable to register cpufreq device"); 303 } 304 return 0; 305 } 306 307 static const struct of_device_id scpi_clocks_ids[] = { 308 { .compatible = "arm,scpi-clocks", }, 309 {} 310 }; 311 MODULE_DEVICE_TABLE(of, scpi_clocks_ids); 312 313 static struct platform_driver scpi_clocks_driver = { 314 .driver = { 315 .name = "scpi_clocks", 316 .of_match_table = scpi_clocks_ids, 317 }, 318 .probe = scpi_clocks_probe, 319 .remove = scpi_clocks_remove, 320 }; 321 module_platform_driver(scpi_clocks_driver); 322 323 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 324 MODULE_DESCRIPTION("ARM SCPI clock driver"); 325 MODULE_LICENSE("GPL v2"); 326