linux/drivers/clk/sunxi/clk-sun9i-core.c
Hans de Goede 6424e0aeeb clk: sunxi: rewrite sun9i_a80_get_pll4_factors()
The old implementation of sun9i_a80_get_pll4_factors() has several issues,
it checks against 256 / 512 in various places where it should use 255 / 511,
it does the wrong thing for low frequencies which are an even multiple of
6 MHz, e.g. if you ask it for 72 MHz it will result in 144 Mhz, and it does
not take into account that n must be at least 12. Moreover it is quite hard
to read / follow it.

This commit rewrites it to be correct in all cases, and makes it much easier
to follow the code / to read.

Cc: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
2015-01-25 16:55:13 +01:00

323 lines
7.1 KiB
C

/*
* Copyright 2014 Chen-Yu Tsai
*
* Chen-Yu Tsai <wens@csie.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/log2.h>
#include "clk-factors.h"
/**
* sun9i_a80_get_pll4_factors() - calculates n, p, m factors for PLL4
* PLL4 rate is calculated as follows
* rate = (parent_rate * n >> p) / (m + 1);
* parent_rate is always 24MHz
*
* p and m are named div1 and div2 in Allwinner's SDK
*/
static void sun9i_a80_get_pll4_factors(u32 *freq, u32 parent_rate,
u8 *n_ret, u8 *k, u8 *m_ret, u8 *p_ret)
{
int n;
int m = 1;
int p = 1;
/* Normalize value to a 6 MHz multiple (24 MHz / 4) */
n = DIV_ROUND_UP(*freq, 6000000);
/* If n is too large switch to steps of 12 MHz */
if (n > 255) {
m = 0;
n = (n + 1) / 2;
}
/* If n is still too large switch to steps of 24 MHz */
if (n > 255) {
p = 0;
n = (n + 1) / 2;
}
/* n must be between 12 and 255 */
if (n > 255)
n = 255;
else if (n < 12)
n = 12;
*freq = ((24000000 * n) >> p) / (m + 1);
/* we were called to round the frequency, we can now return */
if (n_ret == NULL)
return;
*n_ret = n;
*m_ret = m;
*p_ret = p;
}
static struct clk_factors_config sun9i_a80_pll4_config = {
.mshift = 18,
.mwidth = 1,
.nshift = 8,
.nwidth = 8,
.pshift = 16,
.pwidth = 1,
};
static const struct factors_data sun9i_a80_pll4_data __initconst = {
.enable = 31,
.table = &sun9i_a80_pll4_config,
.getter = sun9i_a80_get_pll4_factors,
};
static DEFINE_SPINLOCK(sun9i_a80_pll4_lock);
static void __init sun9i_a80_pll4_setup(struct device_node *node)
{
void __iomem *reg;
reg = of_io_request_and_map(node, 0, of_node_full_name(node));
if (!reg) {
pr_err("Could not get registers for a80-pll4-clk: %s\n",
node->name);
return;
}
sunxi_factors_register(node, &sun9i_a80_pll4_data,
&sun9i_a80_pll4_lock, reg);
}
CLK_OF_DECLARE(sun9i_a80_pll4, "allwinner,sun9i-a80-pll4-clk", sun9i_a80_pll4_setup);
/**
* sun9i_a80_get_gt_factors() - calculates m factor for GT
* GT rate is calculated as follows
* rate = parent_rate / (m + 1);
*/
static void sun9i_a80_get_gt_factors(u32 *freq, u32 parent_rate,
u8 *n, u8 *k, u8 *m, u8 *p)
{
u32 div;
if (parent_rate < *freq)
*freq = parent_rate;
div = DIV_ROUND_UP(parent_rate, *freq);
/* maximum divider is 4 */
if (div > 4)
div = 4;
*freq = parent_rate / div;
/* we were called to round the frequency, we can now return */
if (!m)
return;
*m = div;
}
static struct clk_factors_config sun9i_a80_gt_config = {
.mshift = 0,
.mwidth = 2,
};
static const struct factors_data sun9i_a80_gt_data __initconst = {
.mux = 24,
.muxmask = BIT(1) | BIT(0),
.table = &sun9i_a80_gt_config,
.getter = sun9i_a80_get_gt_factors,
};
static DEFINE_SPINLOCK(sun9i_a80_gt_lock);
static void __init sun9i_a80_gt_setup(struct device_node *node)
{
void __iomem *reg;
struct clk *gt;
reg = of_io_request_and_map(node, 0, of_node_full_name(node));
if (!reg) {
pr_err("Could not get registers for a80-gt-clk: %s\n",
node->name);
return;
}
gt = sunxi_factors_register(node, &sun9i_a80_gt_data,
&sun9i_a80_gt_lock, reg);
/* The GT bus clock needs to be always enabled */
__clk_get(gt);
clk_prepare_enable(gt);
}
CLK_OF_DECLARE(sun9i_a80_gt, "allwinner,sun9i-a80-gt-clk", sun9i_a80_gt_setup);
/**
* sun9i_a80_get_ahb_factors() - calculates p factor for AHB0/1/2
* AHB rate is calculated as follows
* rate = parent_rate >> p;
*/
static void sun9i_a80_get_ahb_factors(u32 *freq, u32 parent_rate,
u8 *n, u8 *k, u8 *m, u8 *p)
{
u32 _p;
if (parent_rate < *freq)
*freq = parent_rate;
_p = order_base_2(DIV_ROUND_UP(parent_rate, *freq));
/* maximum p is 3 */
if (_p > 3)
_p = 3;
*freq = parent_rate >> _p;
/* we were called to round the frequency, we can now return */
if (!p)
return;
*p = _p;
}
static struct clk_factors_config sun9i_a80_ahb_config = {
.pshift = 0,
.pwidth = 2,
};
static const struct factors_data sun9i_a80_ahb_data __initconst = {
.mux = 24,
.muxmask = BIT(1) | BIT(0),
.table = &sun9i_a80_ahb_config,
.getter = sun9i_a80_get_ahb_factors,
};
static DEFINE_SPINLOCK(sun9i_a80_ahb_lock);
static void __init sun9i_a80_ahb_setup(struct device_node *node)
{
void __iomem *reg;
reg = of_io_request_and_map(node, 0, of_node_full_name(node));
if (!reg) {
pr_err("Could not get registers for a80-ahb-clk: %s\n",
node->name);
return;
}
sunxi_factors_register(node, &sun9i_a80_ahb_data,
&sun9i_a80_ahb_lock, reg);
}
CLK_OF_DECLARE(sun9i_a80_ahb, "allwinner,sun9i-a80-ahb-clk", sun9i_a80_ahb_setup);
static const struct factors_data sun9i_a80_apb0_data __initconst = {
.mux = 24,
.muxmask = BIT(0),
.table = &sun9i_a80_ahb_config,
.getter = sun9i_a80_get_ahb_factors,
};
static DEFINE_SPINLOCK(sun9i_a80_apb0_lock);
static void __init sun9i_a80_apb0_setup(struct device_node *node)
{
void __iomem *reg;
reg = of_io_request_and_map(node, 0, of_node_full_name(node));
if (!reg) {
pr_err("Could not get registers for a80-apb0-clk: %s\n",
node->name);
return;
}
sunxi_factors_register(node, &sun9i_a80_apb0_data,
&sun9i_a80_apb0_lock, reg);
}
CLK_OF_DECLARE(sun9i_a80_apb0, "allwinner,sun9i-a80-apb0-clk", sun9i_a80_apb0_setup);
/**
* sun9i_a80_get_apb1_factors() - calculates m, p factors for APB1
* APB1 rate is calculated as follows
* rate = (parent_rate >> p) / (m + 1);
*/
static void sun9i_a80_get_apb1_factors(u32 *freq, u32 parent_rate,
u8 *n, u8 *k, u8 *m, u8 *p)
{
u32 div;
u8 calcm, calcp;
if (parent_rate < *freq)
*freq = parent_rate;
div = DIV_ROUND_UP(parent_rate, *freq);
/* Highest possible divider is 256 (p = 3, m = 31) */
if (div > 256)
div = 256;
calcp = order_base_2(div);
calcm = (parent_rate >> calcp) - 1;
*freq = (parent_rate >> calcp) / (calcm + 1);
/* we were called to round the frequency, we can now return */
if (n == NULL)
return;
*m = calcm;
*p = calcp;
}
static struct clk_factors_config sun9i_a80_apb1_config = {
.mshift = 0,
.mwidth = 5,
.pshift = 16,
.pwidth = 2,
};
static const struct factors_data sun9i_a80_apb1_data __initconst = {
.mux = 24,
.muxmask = BIT(0),
.table = &sun9i_a80_apb1_config,
.getter = sun9i_a80_get_apb1_factors,
};
static DEFINE_SPINLOCK(sun9i_a80_apb1_lock);
static void __init sun9i_a80_apb1_setup(struct device_node *node)
{
void __iomem *reg;
reg = of_io_request_and_map(node, 0, of_node_full_name(node));
if (!reg) {
pr_err("Could not get registers for a80-apb1-clk: %s\n",
node->name);
return;
}
sunxi_factors_register(node, &sun9i_a80_apb1_data,
&sun9i_a80_apb1_lock, reg);
}
CLK_OF_DECLARE(sun9i_a80_apb1, "allwinner,sun9i-a80-apb1-clk", sun9i_a80_apb1_setup);