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