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

   1 /*
   2  * Copyright 2014 Chen-Yu Tsai
   3  *
   4  * Chen-Yu Tsai <wens@csie.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/clk-provider.h>
  18 #include <linux/clkdev.h>
  19 #include <linux/of_address.h>
  20
  21 #include "clk-factors.h"
  22
  23 /**
  24  * sun8i_a23_get_mbus_factors() - calculates m factor for MBUS clocks
  25  * MBUS rate is calculated as follows
  26  * rate = parent_rate / (m + 1);
  27  */
  28
  29 static void sun8i_a23_get_mbus_factors(u32 *freq, u32 parent_rate,
  30                                        u8 *n, u8 *k, u8 *m, u8 *p)
  31 {
  32         u8 div;
  33
  34         /*
  35          * These clocks can only divide, so we will never be able to
  36          * achieve frequencies higher than the parent frequency
  37          */
  38         if (*freq > parent_rate)
  39                 *freq = parent_rate;
  40
  41         div = DIV_ROUND_UP(parent_rate, *freq);
  42
  43         if (div > 8)
  44                 div = 8;
  45
  46         *freq = parent_rate / div;
  47
  48         /* we were called to round the frequency, we can now return */
  49         if (m == NULL)
  50                 return;
  51
  52         *m = div - 1;
  53 }
  54
  55 static struct clk_factors_config sun8i_a23_mbus_config = {
  56         .mshift = 0,
  57         .mwidth = 3,
  58 };
  59
  60 static const struct factors_data sun8i_a23_mbus_data __initconst = {
  61         .enable = 31,
  62         .mux = 24,
  63         .muxmask = BIT(1) | BIT(0),
  64         .table = &sun8i_a23_mbus_config,
  65         .getter = sun8i_a23_get_mbus_factors,
  66 };
  67
  68 static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
  69
  70 static void __init sun8i_a23_mbus_setup(struct device_node *node)
  71 {
  72         struct clk *mbus;
  73         void __iomem *reg;
  74
  75         reg = of_iomap(node, 0);
  76         if (!reg) {
  77                 pr_err("Could not get registers for a23-mbus-clk\n");
  78                 return;
  79         }
  80
  81         mbus = sunxi_factors_register(node, &sun8i_a23_mbus_data,
  82                                       &sun8i_a23_mbus_lock, reg);
  83
  84         /* The MBUS clocks needs to be always enabled */
  85         __clk_get(mbus);
  86         clk_prepare_enable(mbus);
  87 }
  88 CLK_OF_DECLARE(sun8i_a23_mbus, "allwinner,sun8i-a23-mbus-clk", sun8i_a23_mbus_setup);