LXR linux/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 */
  26static 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
  56static const struct clk_factors_config sun6i_ar100_config = {
  57        .mwidth = 5,
  58        .mshift = 8,
  59        .pwidth = 2,
  60        .pshift = 4,
  61};
  62
  63static 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
  70static DEFINE_SPINLOCK(sun6i_ar100_lock);
  71
  72static 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
  94static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
  95        { .compatible = "allwinner,sun6i-a31-ar100-clk" },
  96        { /* sentinel */ }
  97};
  98
  99static 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};
 107builtin_platform_driver(sun6i_a31_ar100_clk_driver);
 108