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, struct_size(clk_data, hws, count), 141 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"); 195