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.h> 18 #include <linux/clk-provider.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); 89