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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2014 Free Electrons
   4  *
   5  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
   6  *
   7  * Allwinner A31 AR100 clock driver
   8  */
   9
  10 #include <linux/bitops.h>
  11 #include <linux/clk-provider.h>
  12 #include <linux/init.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/spinlock.h>
  16
  17 #include "clk-factors.h"
  18
  19 /**
  20  * sun6i_get_ar100_factors - Calculates factors p, m for AR100
  21  *
  22  * AR100 rate is calculated as follows
  23  * rate = (parent_rate >> p) / (m + 1);
  24  */
  25 static void sun6i_get_ar100_factors(struct factors_request *req)
  26 {
  27         unsigned long div;
  28         int shift;
  29
  30         /* clock only divides */
  31         if (req->rate > req->parent_rate)
  32                 req->rate = req->parent_rate;
  33
  34         div = DIV_ROUND_UP(req->parent_rate, req->rate);
  35
  36         if (div < 32)
  37                 shift = 0;
  38         else if (div >> 1 < 32)
  39                 shift = 1;
  40         else if (div >> 2 < 32)
  41                 shift = 2;
  42         else
  43                 shift = 3;
  44
  45         div >>= shift;
  46
  47         if (div > 32)
  48                 div = 32;
  49
  50         req->rate = (req->parent_rate >> shift) / div;
  51         req->m = div - 1;
  52         req->p = shift;
  53 }
  54
  55 static const struct clk_factors_config sun6i_ar100_config = {
  56         .mwidth = 5,
  57         .mshift = 8,
  58         .pwidth = 2,
  59         .pshift = 4,
  60 };
  61
  62 static const struct factors_data sun6i_ar100_data = {
  63         .mux = 16,
  64         .muxmask = GENMASK(1, 0),
  65         .table = &sun6i_ar100_config,
  66         .getter = sun6i_get_ar100_factors,
  67 };
  68
  69 static DEFINE_SPINLOCK(sun6i_ar100_lock);
  70
  71 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
  72 {
  73         struct device_node *np = pdev->dev.of_node;
  74         struct resource *r;
  75         void __iomem *reg;
  76         struct clk *clk;
  77
  78         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  79         reg = devm_ioremap_resource(&pdev->dev, r);
  80         if (IS_ERR(reg))
  81                 return PTR_ERR(reg);
  82
  83         clk = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
  84                                      reg);
  85         if (!clk)
  86                 return -ENOMEM;
  87
  88         platform_set_drvdata(pdev, clk);
  89
  90         return 0;
  91 }
  92
  93 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
  94         { .compatible = "allwinner,sun6i-a31-ar100-clk" },
  95         { /* sentinel */ }
  96 };
  97
  98 static struct platform_driver sun6i_a31_ar100_clk_driver = {
  99         .driver = {
 100                 .name = "sun6i-a31-ar100-clk",
 101                 .of_match_table = sun6i_a31_ar100_clk_dt_ids,
 102                 .suppress_bind_attrs = true,
 103         },
 104         .probe = sun6i_a31_ar100_clk_probe,
 105 };
 106 builtin_platform_driver(sun6i_a31_ar100_clk_driver);