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// SPDX-License-Identifier: GPL-2.0+
/*
* TI divider clock support
*
* Copyright (C) 2020 Dario Binacchi <dariobin@libero.it>
*
* Loosely based on Linux kernel drivers/clk/ti/divider.c
*/
#include <clk.h>
#include <clk-uclass.h>
#include <div64.h>
#include <dm.h>
#include <dm/device_compat.h>
#include <asm/io.h>
#include <linux/clk-provider.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include "clk.h"
/*
* The reverse of DIV_ROUND_UP: The maximum number which
* divided by m is r
*/
#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
struct clk_ti_divider_priv {
struct clk parent;
struct clk_ti_reg reg;
const struct clk_div_table *table;
u8 shift;
u8 flags;
u8 div_flags;
s8 latch;
u16 min;
u16 max;
u16 mask;
};
static unsigned int _get_div(const struct clk_div_table *table, ulong flags,
unsigned int val)
{
if (flags & CLK_DIVIDER_ONE_BASED)
return val;
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return 1 << val;
if (table)
return clk_divider_get_table_div(table, val);
return val + 1;
}
static unsigned int _get_val(const struct clk_div_table *table, ulong flags,
unsigned int div)
{
if (flags & CLK_DIVIDER_ONE_BASED)
return div;
if (flags & CLK_DIVIDER_POWER_OF_TWO)
return __ffs(div);
if (table)
return clk_divider_get_table_val(table, div);
return div - 1;
}
static int _div_round_up(const struct clk_div_table *table, ulong parent_rate,
ulong rate)
{
const struct clk_div_table *clkt;
int up = INT_MAX;
int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
for (clkt = table; clkt->div; clkt++) {
if (clkt->div == div)
return clkt->div;
else if (clkt->div < div)
continue;
if ((clkt->div - div) < (up - div))
up = clkt->div;
}
return up;
}
static int _div_round(const struct clk_div_table *table, ulong parent_rate,
ulong rate)
{
if (table)
return _div_round_up(table, parent_rate, rate);
return DIV_ROUND_UP(parent_rate, rate);
}
static int clk_ti_divider_best_div(struct clk *clk, ulong rate,
ulong *best_parent_rate)
{
struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
ulong parent_rate, parent_round_rate, max_div;
ulong best_rate, r;
int i, best_div = 0;
parent_rate = clk_get_rate(&priv->parent);
if (IS_ERR_VALUE(parent_rate))
return parent_rate;
if (!rate)
rate = 1;
if (!(clk->flags & CLK_SET_RATE_PARENT)) {
best_div = _div_round(priv->table, parent_rate, rate);
if (best_div == 0)
best_div = 1;
if (best_div > priv->max)
best_div = priv->max;
*best_parent_rate = parent_rate;
return best_div;
}
max_div = min(ULONG_MAX / rate, (ulong)priv->max);
for (best_rate = 0, i = 1; i <= max_div; i++) {
if (!clk_divider_is_valid_div(priv->table, priv->div_flags, i))
continue;
/*
* It's the most ideal case if the requested rate can be
* divided from parent clock without needing to change
* parent rate, so return the divider immediately.
*/
if ((rate * i) == parent_rate) {
*best_parent_rate = parent_rate;
dev_dbg(clk->dev, "rate=%ld, best_rate=%ld, div=%d\n",
rate, rate, i);
return i;
}
parent_round_rate = clk_round_rate(&priv->parent,
MULT_ROUND_UP(rate, i));
if (IS_ERR_VALUE(parent_round_rate))
continue;
r = DIV_ROUND_UP(parent_round_rate, i);
if (r <= rate && r > best_rate) {
best_div = i;
best_rate = r;
*best_parent_rate = parent_round_rate;
if (best_rate == rate)
break;
}
}
if (best_div == 0) {
best_div = priv->max;
parent_round_rate = clk_round_rate(&priv->parent, 1);
if (IS_ERR_VALUE(parent_round_rate))
return parent_round_rate;
}
dev_dbg(clk->dev, "rate=%ld, best_rate=%ld, div=%d\n", rate, best_rate,
best_div);
return best_div;
}
static ulong clk_ti_divider_round_rate(struct clk *clk, ulong rate)
{
ulong parent_rate;
int div;
div = clk_ti_divider_best_div(clk, rate, &parent_rate);
if (div < 0)
return div;
return DIV_ROUND_UP(parent_rate, div);
}
static ulong clk_ti_divider_set_rate(struct clk *clk, ulong rate)
{
struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
ulong parent_rate;
int div;
u32 val, v;
div = clk_ti_divider_best_div(clk, rate, &parent_rate);
if (div < 0)
return div;
if (clk->flags & CLK_SET_RATE_PARENT) {
parent_rate = clk_set_rate(&priv->parent, parent_rate);
if (IS_ERR_VALUE(parent_rate))
return parent_rate;
}
val = _get_val(priv->table, priv->div_flags, div);
v = clk_ti_readl(&priv->reg);
v &= ~(priv->mask << priv->shift);
v |= val << priv->shift;
clk_ti_writel(v, &priv->reg);
clk_ti_latch(&priv->reg, priv->latch);
return clk_get_rate(clk);
}
static ulong clk_ti_divider_get_rate(struct clk *clk)
{
struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
ulong rate, parent_rate;
unsigned int div;
u32 v;
parent_rate = clk_get_rate(&priv->parent);
if (IS_ERR_VALUE(parent_rate))
return parent_rate;
v = clk_ti_readl(&priv->reg) >> priv->shift;
v &= priv->mask;
div = _get_div(priv->table, priv->div_flags, v);
if (!div) {
if (!(priv->div_flags & CLK_DIVIDER_ALLOW_ZERO))
dev_warn(clk->dev,
"zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n");
return parent_rate;
}
rate = DIV_ROUND_UP(parent_rate, div);
dev_dbg(clk->dev, "rate=%ld\n", rate);
return rate;
}
static int clk_ti_divider_request(struct clk *clk)
{
struct clk_ti_divider_priv *priv = dev_get_priv(clk->dev);
clk->flags = priv->flags;
return 0;
}
const struct clk_ops clk_ti_divider_ops = {
.request = clk_ti_divider_request,
.round_rate = clk_ti_divider_round_rate,
.get_rate = clk_ti_divider_get_rate,
.set_rate = clk_ti_divider_set_rate
};
static int clk_ti_divider_remove(struct udevice *dev)
{
struct clk_ti_divider_priv *priv = dev_get_priv(dev);
int err;
err = clk_release_all(&priv->parent, 1);
if (err) {
dev_err(dev, "failed to release parent clock\n");
return err;
}
return 0;
}
static int clk_ti_divider_probe(struct udevice *dev)
{
struct clk_ti_divider_priv *priv = dev_get_priv(dev);
int err;
err = clk_get_by_index(dev, 0, &priv->parent);
if (err) {
dev_err(dev, "failed to get parent clock\n");
return err;
}
return 0;
}
static int clk_ti_divider_of_to_plat(struct udevice *dev)
{
struct clk_ti_divider_priv *priv = dev_get_priv(dev);
struct clk_div_table *table = NULL;
u32 val, valid_div;
u32 min_div = 0;
u32 max_val, max_div = 0;
u16 mask;
int i, div_num, err;
err = clk_ti_get_reg_addr(dev, 0, &priv->reg);
if (err) {
dev_err(dev, "failed to get register address\n");
return err;
}
priv->shift = dev_read_u32_default(dev, "ti,bit-shift", 0);
priv->latch = dev_read_s32_default(dev, "ti,latch-bit", -EINVAL);
if (dev_read_bool(dev, "ti,index-starts-at-one"))
priv->div_flags |= CLK_DIVIDER_ONE_BASED;
if (dev_read_bool(dev, "ti,index-power-of-two"))
priv->div_flags |= CLK_DIVIDER_POWER_OF_TWO;
if (dev_read_bool(dev, "ti,set-rate-parent"))
priv->flags |= CLK_SET_RATE_PARENT;
if (dev_read_prop(dev, "ti,dividers", &div_num)) {
div_num /= sizeof(u32);
/* Determine required size for divider table */
for (i = 0, valid_div = 0; i < div_num; i++) {
dev_read_u32_index(dev, "ti,dividers", i, &val);
if (val)
valid_div++;
}
if (!valid_div) {
dev_err(dev, "no valid dividers\n");
return -EINVAL;
}
table = calloc(valid_div + 1, sizeof(*table));
if (!table)
return -ENOMEM;
for (i = 0, valid_div = 0; i < div_num; i++) {
dev_read_u32_index(dev, "ti,dividers", i, &val);
if (!val)
continue;
table[valid_div].div = val;
table[valid_div].val = i;
valid_div++;
if (val > max_div)
max_div = val;
if (!min_div || val < min_div)
min_div = val;
}
max_val = max_div;
} else {
/* Divider table not provided, determine min/max divs */
min_div = dev_read_u32_default(dev, "ti,min-div", 1);
if (dev_read_u32(dev, "ti,max-div", &max_div)) {
dev_err(dev, "missing 'max-div' property\n");
return -EFAULT;
}
max_val = max_div;
if (!(priv->div_flags & CLK_DIVIDER_ONE_BASED) &&
!(priv->div_flags & CLK_DIVIDER_POWER_OF_TWO))
max_val--;
}
priv->table = table;
priv->min = min_div;
priv->max = max_div;
if (priv->div_flags & CLK_DIVIDER_POWER_OF_TWO)
mask = fls(max_val) - 1;
else
mask = max_val;
priv->mask = (1 << fls(mask)) - 1;
return 0;
}
static const struct udevice_id clk_ti_divider_of_match[] = {
{.compatible = "ti,divider-clock"},
{}
};
U_BOOT_DRIVER(clk_ti_divider) = {
.name = "ti_divider_clock",
.id = UCLASS_CLK,
.of_match = clk_ti_divider_of_match,
.of_to_plat = clk_ti_divider_of_to_plat,
.probe = clk_ti_divider_probe,
.remove = clk_ti_divider_remove,
.priv_auto = sizeof(struct clk_ti_divider_priv),
.ops = &clk_ti_divider_ops,
};