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