| Maxime Ripard | 992a56e | 2014-07-10 23:55:18 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2013 Emilio López |
| 3 | * |
| 4 | * Emilio López <emilio@elopez.com.ar> |
| 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 | |
| 20 | #include "clk-factors.h" |
| 21 | |
| 22 | /** |
| 23 | * sun4i_get_mod0_factors() - calculates m, n factors for MOD0-style clocks |
| 24 | * MOD0 rate is calculated as follows |
| 25 | * rate = (parent_rate >> p) / (m + 1); |
| 26 | */ |
| 27 | |
| 28 | static void sun4i_a10_get_mod0_factors(u32 *freq, u32 parent_rate, |
| 29 | u8 *n, u8 *k, u8 *m, u8 *p) |
| 30 | { |
| 31 | u8 div, calcm, calcp; |
| 32 | |
| 33 | /* These clocks can only divide, so we will never be able to achieve |
| 34 | * frequencies higher than the parent frequency */ |
| 35 | if (*freq > parent_rate) |
| 36 | *freq = parent_rate; |
| 37 | |
| 38 | div = DIV_ROUND_UP(parent_rate, *freq); |
| 39 | |
| 40 | if (div < 16) |
| 41 | calcp = 0; |
| 42 | else if (div / 2 < 16) |
| 43 | calcp = 1; |
| 44 | else if (div / 4 < 16) |
| 45 | calcp = 2; |
| 46 | else |
| 47 | calcp = 3; |
| 48 | |
| 49 | calcm = DIV_ROUND_UP(div, 1 << calcp); |
| 50 | |
| 51 | *freq = (parent_rate >> calcp) / calcm; |
| 52 | |
| 53 | /* we were called to round the frequency, we can now return */ |
| 54 | if (n == NULL) |
| 55 | return; |
| 56 | |
| 57 | *m = calcm - 1; |
| 58 | *p = calcp; |
| 59 | } |
| 60 | |
| 61 | /* user manual says "n" but it's really "p" */ |
| 62 | static struct clk_factors_config sun4i_a10_mod0_config = { |
| 63 | .mshift = 0, |
| 64 | .mwidth = 4, |
| 65 | .pshift = 16, |
| 66 | .pwidth = 2, |
| 67 | }; |
| 68 | |
| 69 | static const struct factors_data sun4i_a10_mod0_data __initconst = { |
| 70 | .enable = 31, |
| 71 | .mux = 24, |
| 72 | .table = &sun4i_a10_mod0_config, |
| 73 | .getter = sun4i_a10_get_mod0_factors, |
| 74 | }; |
| 75 | |
| 76 | static DEFINE_SPINLOCK(sun4i_a10_mod0_lock); |
| 77 | |
| 78 | static void __init sun4i_a10_mod0_setup(struct device_node *node) |
| 79 | { |
| 80 | sunxi_factors_register(node, &sun4i_a10_mod0_data, &sun4i_a10_mod0_lock); |
| 81 | } |
| 82 | CLK_OF_DECLARE(sun4i_a10_mod0, "allwinner,sun4i-a10-mod0-clk", sun4i_a10_mod0_setup); |