drivers/clk/sunxi/clk-sun6i-ar100.c

   1 /*
   2  * Copyright (C) 2014 Free Electrons
   3  *
   4  * License Terms: GNU General Public License v2
   5  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
   6  *
   7  * Allwinner A31 AR100 clock driver
   8  *
   9  */
  10
  11 #include <linux/bitops.h>
  12 #include <linux/clk-provider.h>
  13 #include <linux/init.h>
  14 #include <linux/of.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/spinlock.h>
  17
  18 #include "clk-factors.h"
  19
  20 /**
  21  * sun6i_get_ar100_factors - Calculates factors p, m for AR100
  22  *
  23  * AR100 rate is calculated as follows
  24  * rate = (parent_rate >> p) / (m + 1);
  25  */
  26 static void sun6i_get_ar100_factors(struct factors_request *req)
  27 {
  28         unsigned long div;
  29         int shift;
  30
  31         /* clock only divides */
  32         if (req->rate > req->parent_rate)
  33                 req->rate = req->parent_rate;
  34
  35         div = DIV_ROUND_UP(req->parent_rate, req->rate);
  36
  37         if (div < 32)
  38                 shift = 0;
  39         else if (div >> 1 < 32)
  40                 shift = 1;
  41         else if (div >> 2 < 32)
  42                 shift = 2;
  43         else
  44                 shift = 3;
  45
  46         div >>= shift;
  47
  48         if (div > 32)
  49                 div = 32;
  50
  51         req->rate = (req->parent_rate >> shift) / div;
  52         req->m = div - 1;
  53         req->p = shift;
  54 }
  55
  56 static const struct clk_factors_config sun6i_ar100_config = {
  57         .mwidth = 5,
  58         .mshift = 8,
  59         .pwidth = 2,
  60         .pshift = 4,
  61 };
  62
  63 static const struct factors_data sun6i_ar100_data = {
  64         .mux = 16,
  65         .muxmask = GENMASK(1, 0),
  66         .table = &sun6i_ar100_config,
  67         .getter = sun6i_get_ar100_factors,
  68 };
  69
  70 static DEFINE_SPINLOCK(sun6i_ar100_lock);
  71
  72 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
  73 {
  74         struct device_node *np = pdev->dev.of_node;
  75         struct resource *r;
  76         void __iomem *reg;
  77         struct clk *clk;
  78
  79         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  80         reg = devm_ioremap_resource(&pdev->dev, r);
  81         if (IS_ERR(reg))
  82                 return PTR_ERR(reg);
  83
  84         clk = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
  85                                      reg);
  86         if (!clk)
  87                 return -ENOMEM;
  88
  89         platform_set_drvdata(pdev, clk);
  90
  91         return 0;
  92 }
  93
  94 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
  95         { .compatible = "allwinner,sun6i-a31-ar100-clk" },
  96         { /* sentinel */ }
  97 };
  98
  99 static struct platform_driver sun6i_a31_ar100_clk_driver = {
 100         .driver = {
 101                 .name = "sun6i-a31-ar100-clk",
 102                 .of_match_table = sun6i_a31_ar100_clk_dt_ids,
 103                 .suppress_bind_attrs = true,
 104         },
 105         .probe = sun6i_a31_ar100_clk_probe,
 106 };
 107 builtin_platform_driver(sun6i_a31_ar100_clk_driver);