drivers/clk/sunxi/clk-sun8i-apb0.c

   1 /*
   2  * Copyright (C) 2014 Chen-Yu Tsai
   3  * Author: Chen-Yu Tsai <wens@csie.org>
   4  *
   5  * Allwinner A23 APB0 clock driver
   6  *
   7  * License Terms: GNU General Public License v2
   8  *
   9  * Based on clk-sun6i-apb0.c
  10  * Allwinner A31 APB0 clock driver
  11  *
  12  * Copyright (C) 2014 Free Electrons
  13  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
  14  *
  15  */
  16
  17 #include <linux/clk-provider.h>
  18 #include <linux/init.h>
  19 #include <linux/of.h>
  20 #include <linux/of_address.h>
  21 #include <linux/platform_device.h>
  22
  23 static struct clk *sun8i_a23_apb0_register(struct device_node *node,
  24                                            void __iomem *reg)
  25 {
  26         const char *clk_name = node->name;
  27         const char *clk_parent;
  28         struct clk *clk;
  29         int ret;
  30
  31         clk_parent = of_clk_get_parent_name(node, 0);
  32         if (!clk_parent)
  33                 return ERR_PTR(-EINVAL);
  34
  35         of_property_read_string(node, "clock-output-names", &clk_name);
  36
  37         /* The A23 APB0 clock is a standard 2 bit wide divider clock */
  38         clk = clk_register_divider(NULL, clk_name, clk_parent, 0, reg,
  39                                    0, 2, 0, NULL);
  40         if (IS_ERR(clk))
  41                 return clk;
  42
  43         ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
  44         if (ret)
  45                 goto err_unregister;
  46
  47         return clk;
  48
  49 err_unregister:
  50         clk_unregister_divider(clk);
  51
  52         return ERR_PTR(ret);
  53 }
  54
  55 static void sun8i_a23_apb0_setup(struct device_node *node)
  56 {
  57         void __iomem *reg;
  58         struct resource res;
  59         struct clk *clk;
  60
  61         reg = of_io_request_and_map(node, 0, of_node_full_name(node));
  62         if (IS_ERR(reg)) {
  63                 /*
  64                  * This happens with clk nodes instantiated through mfd,
  65                  * as those do not have their resources assigned in the
  66                  * device tree. Do not print an error in this case.
  67                  */
  68                 if (PTR_ERR(reg) != -EINVAL)
  69                         pr_err("Could not get registers for a23-apb0-clk\n");
  70
  71                 return;
  72         }
  73
  74         clk = sun8i_a23_apb0_register(node, reg);
  75         if (IS_ERR(clk))
  76                 goto err_unmap;
  77
  78         return;
  79
  80 err_unmap:
  81         iounmap(reg);
  82         of_address_to_resource(node, 0, &res);
  83         release_mem_region(res.start, resource_size(&res));
  84 }
  85 CLK_OF_DECLARE_DRIVER(sun8i_a23_apb0, "allwinner,sun8i-a23-apb0-clk",
  86                       sun8i_a23_apb0_setup);
  87
  88 static int sun8i_a23_apb0_clk_probe(struct platform_device *pdev)
  89 {
  90         struct device_node *np = pdev->dev.of_node;
  91         struct resource *r;
  92         void __iomem *reg;
  93         struct clk *clk;
  94
  95         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  96         reg = devm_ioremap_resource(&pdev->dev, r);
  97         if (IS_ERR(reg))
  98                 return PTR_ERR(reg);
  99
 100         clk = sun8i_a23_apb0_register(np, reg);
 101         return PTR_ERR_OR_ZERO(clk);
 102 }
 103
 104 static const struct of_device_id sun8i_a23_apb0_clk_dt_ids[] = {
 105         { .compatible = "allwinner,sun8i-a23-apb0-clk" },
 106         { /* sentinel */ }
 107 };
 108
 109 static struct platform_driver sun8i_a23_apb0_clk_driver = {
 110         .driver = {
 111                 .name = "sun8i-a23-apb0-clk",
 112                 .of_match_table = sun8i_a23_apb0_clk_dt_ids,
 113         },
 114         .probe = sun8i_a23_apb0_clk_probe,
 115 };
 116 builtin_platform_driver(sun8i_a23_apb0_clk_driver);