// SPDX-License-Identifier: GPL-2.0
  /*
   * System Control and Power Interface (SCMI) Protocol based clock driver
   *
   * Copyright (C) 2018 ARM Ltd.
   */
  
  #include <linux/clk-provider.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/of.h>
  #include <linux/module.h>
  #include <linux/scmi_protocol.h>
  #include <asm/div64.h>
  
  struct scmi_clk {
  	u32 id;
  	struct clk_hw hw;
  	const struct scmi_clock_info *info;
  	const struct scmi_handle *handle;
  };
  
  #define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
  
  static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
  					  unsigned long parent_rate)
  {
  	int ret;
  	u64 rate;
  	struct scmi_clk *clk = to_scmi_clk(hw);
  
  	ret = clk->handle->clk_ops->rate_get(clk->handle, clk->id, &rate);
  	if (ret)
  		return 0;
  	return rate;
  }
  
  static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
  				unsigned long *parent_rate)
  {

  	u64 fmin, fmax, ftmp;
  	struct scmi_clk *clk = to_scmi_clk(hw);
  
  	/*
  	 * We can't figure out what rate it will be, so just return the
  	 * rate back to the caller. scmi_clk_recalc_rate() will be called
  	 * after the rate is set and we'll know what rate the clock is
  	 * running at then.
  	 */
  	if (clk->info->rate_discrete)
  		return rate;
  
  	fmin = clk->info->range.min_rate;
  	fmax = clk->info->range.max_rate;
  	if (rate <= fmin)
  		return fmin;
  	else if (rate >= fmax)
  		return fmax;
  
  	ftmp = rate - fmin;
  	ftmp += clk->info->range.step_size - 1; /* to round up */

  	do_div(ftmp, clk->info->range.step_size);

  	return ftmp * clk->info->range.step_size + fmin;

  }
  
  static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
  			     unsigned long parent_rate)
  {
  	struct scmi_clk *clk = to_scmi_clk(hw);

  	return clk->handle->clk_ops->rate_set(clk->handle, clk->id, rate);

  }
  
  static int scmi_clk_enable(struct clk_hw *hw)
  {
  	struct scmi_clk *clk = to_scmi_clk(hw);
  
  	return clk->handle->clk_ops->enable(clk->handle, clk->id);
  }
  
  static void scmi_clk_disable(struct clk_hw *hw)
  {
  	struct scmi_clk *clk = to_scmi_clk(hw);
  
  	clk->handle->clk_ops->disable(clk->handle, clk->id);
  }
  
  static const struct clk_ops scmi_clk_ops = {
  	.recalc_rate = scmi_clk_recalc_rate,
  	.round_rate = scmi_clk_round_rate,
  	.set_rate = scmi_clk_set_rate,
  	/*
  	 * We can't provide enable/disable callback as we can't perform the same
  	 * in atomic context. Since the clock framework provides standard API
  	 * clk_prepare_enable that helps cases using clk_enable in non-atomic
  	 * context, it should be fine providing prepare/unprepare.
  	 */
  	.prepare = scmi_clk_enable,
  	.unprepare = scmi_clk_disable,
  };
  
  static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
  {
  	int ret;

  	unsigned long min_rate, max_rate;

  	struct clk_init_data init = {
  		.flags = CLK_GET_RATE_NOCACHE,
  		.num_parents = 0,
  		.ops = &scmi_clk_ops,
  		.name = sclk->info->name,
  	};
  
  	sclk->hw.init = &init;
  	ret = devm_clk_hw_register(dev, &sclk->hw);

  	if (ret)
  		return ret;
  
  	if (sclk->info->rate_discrete) {
  		int num_rates = sclk->info->list.num_rates;
  
  		if (num_rates <= 0)
  			return -EINVAL;
  
  		min_rate = sclk->info->list.rates[0];
  		max_rate = sclk->info->list.rates[num_rates - 1];
  	} else {
  		min_rate = sclk->info->range.min_rate;
  		max_rate = sclk->info->range.max_rate;
  	}
  
  	clk_hw_set_rate_range(&sclk->hw, min_rate, max_rate);

  	return ret;
  }
  
  static int scmi_clocks_probe(struct scmi_device *sdev)
  {
  	int idx, count, err;
  	struct clk_hw **hws;
  	struct clk_hw_onecell_data *clk_data;
  	struct device *dev = &sdev->dev;
  	struct device_node *np = dev->of_node;
  	const struct scmi_handle *handle = sdev->handle;
  
  	if (!handle || !handle->clk_ops)
  		return -ENODEV;
  
  	count = handle->clk_ops->count_get(handle);
  	if (count < 0) {

  		dev_err(dev, "%pOFn: invalid clock output count
  ", np);

  		return -EINVAL;
  	}

  	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, count),
  				GFP_KERNEL);

  	if (!clk_data)
  		return -ENOMEM;
  
  	clk_data->num = count;
  	hws = clk_data->hws;
  
  	for (idx = 0; idx < count; idx++) {
  		struct scmi_clk *sclk;
  
  		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
  		if (!sclk)
  			return -ENOMEM;
  
  		sclk->info = handle->clk_ops->info_get(handle, idx);
  		if (!sclk->info) {
  			dev_dbg(dev, "invalid clock info for idx %d
  ", idx);
  			continue;
  		}
  
  		sclk->id = idx;
  		sclk->handle = handle;
  
  		err = scmi_clk_ops_init(dev, sclk);
  		if (err) {
  			dev_err(dev, "failed to register clock %d
  ", idx);
  			devm_kfree(dev, sclk);
  			hws[idx] = NULL;
  		} else {
  			dev_dbg(dev, "Registered clock:%s
  ", sclk->info->name);
  			hws[idx] = &sclk->hw;
  		}
  	}

  	return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
  					   clk_data);

  }
  
  static const struct scmi_device_id scmi_id_table[] = {

  	{ SCMI_PROTOCOL_CLOCK, "clocks" },

  	{ },
  };
  MODULE_DEVICE_TABLE(scmi, scmi_id_table);
  
  static struct scmi_driver scmi_clocks_driver = {
  	.name = "scmi-clocks",
  	.probe = scmi_clocks_probe,

  	.id_table = scmi_id_table,
  };
  module_scmi_driver(scmi_clocks_driver);
  
  MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
  MODULE_DESCRIPTION("ARM SCMI clock driver");
  MODULE_LICENSE("GPL v2");