drivers/clk/clk-scmi.c

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