/*
   * Copyright (C) 2014 Chen-Yu Tsai
   * Author: Chen-Yu Tsai <wens@csie.org>
   *
   * Allwinner A23 APB0 clock driver
   *
   * License Terms: GNU General Public License v2
   *
   * Based on clk-sun6i-apb0.c
   * Allwinner A31 APB0 clock driver
   *
   * Copyright (C) 2014 Free Electrons
   * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
   *
   */
  
  #include <linux/clk-provider.h>

  #include <linux/init.h>

  #include <linux/of.h>

  #include <linux/of_address.h>

  #include <linux/platform_device.h>

  static struct clk *sun8i_a23_apb0_register(struct device_node *node,
  					   void __iomem *reg)
  {
  	const char *clk_name = node->name;
  	const char *clk_parent;
  	struct clk *clk;
  	int ret;
  
  	clk_parent = of_clk_get_parent_name(node, 0);
  	if (!clk_parent)
  		return ERR_PTR(-EINVAL);
  
  	of_property_read_string(node, "clock-output-names", &clk_name);
  
  	/* The A23 APB0 clock is a standard 2 bit wide divider clock */
  	clk = clk_register_divider(NULL, clk_name, clk_parent, 0, reg,

  				   0, 2, 0, NULL);

  	if (IS_ERR(clk))
  		return clk;
  
  	ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
  	if (ret)
  		goto err_unregister;
  
  	return clk;
  
  err_unregister:
  	clk_unregister_divider(clk);
  
  	return ERR_PTR(ret);
  }
  
  static void sun8i_a23_apb0_setup(struct device_node *node)
  {
  	void __iomem *reg;
  	struct resource res;
  	struct clk *clk;
  
  	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
  	if (IS_ERR(reg)) {
  		/*
  		 * This happens with clk nodes instantiated through mfd,
  		 * as those do not have their resources assigned in the
  		 * device tree. Do not print an error in this case.
  		 */
  		if (PTR_ERR(reg) != -EINVAL)
  			pr_err("Could not get registers for a23-apb0-clk
  ");
  
  		return;
  	}
  
  	clk = sun8i_a23_apb0_register(node, reg);
  	if (IS_ERR(clk))
  		goto err_unmap;
  
  	return;
  
  err_unmap:
  	iounmap(reg);
  	of_address_to_resource(node, 0, &res);
  	release_mem_region(res.start, resource_size(&res));
  }

  CLK_OF_DECLARE_DRIVER(sun8i_a23_apb0, "allwinner,sun8i-a23-apb0-clk",
  		      sun8i_a23_apb0_setup);

  static int sun8i_a23_apb0_clk_probe(struct platform_device *pdev)
  {
  	struct device_node *np = pdev->dev.of_node;

  	struct resource *r;
  	void __iomem *reg;
  	struct clk *clk;
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	reg = devm_ioremap_resource(&pdev->dev, r);
  	if (IS_ERR(reg))
  		return PTR_ERR(reg);

  	clk = sun8i_a23_apb0_register(np, reg);

  	if (IS_ERR(clk))
  		return PTR_ERR(clk);

  	return 0;

  }

  static const struct of_device_id sun8i_a23_apb0_clk_dt_ids[] = {

  	{ .compatible = "allwinner,sun8i-a23-apb0-clk" },
  	{ /* sentinel */ }
  };
  
  static struct platform_driver sun8i_a23_apb0_clk_driver = {
  	.driver = {
  		.name = "sun8i-a23-apb0-clk",

  		.of_match_table = sun8i_a23_apb0_clk_dt_ids,
  	},
  	.probe = sun8i_a23_apb0_clk_probe,
  };

  builtin_platform_driver(sun8i_a23_apb0_clk_driver);