drivers/clk/clk-scpi.c

   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");