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/*
* Copyright (c) 2015 Endless Mobile, Inc.
* Author: Carlo Caione <carlo@endlessm.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* In the most basic form, a Meson PLL is composed as follows:
*
* PLL
* +------------------------------+
* | |
* in -----[ /N ]---[ *M ]---[ >>OD ]----->> out
* | ^ ^ |
* +------------------------------+
* | |
* FREF VCO
*
* out = (in * M / N) >> OD
*/
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "clkc.h"
#define MESON_PLL_RESET BIT(29)
#define MESON_PLL_LOCK BIT(31)
#define to_meson_clk_pll(_hw) container_of(_hw, struct meson_clk_pll, hw)
static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct meson_clk_pll *pll = to_meson_clk_pll(hw);
struct parm *p;
unsigned long parent_rate_mhz = parent_rate / 1000000;
unsigned long rate_mhz;
u16 n, m, frac = 0, od, od2 = 0;
u32 reg;
p = &pll->n;
reg = readl(pll->base + p->reg_off);
n = PARM_GET(p->width, p->shift, reg);
p = &pll->m;
reg = readl(pll->base + p->reg_off);
m = PARM_GET(p->width, p->shift, reg);
p = &pll->od;
reg = readl(pll->base + p->reg_off);
od = PARM_GET(p->width, p->shift, reg);
p = &pll->od2;
if (p->width) {
reg = readl(pll->base + p->reg_off);
od2 = PARM_GET(p->width, p->shift, reg);
}
p = &pll->frac;
if (p->width) {
reg = readl(pll->base + p->reg_off);
frac = PARM_GET(p->width, p->shift, reg);
rate_mhz = (parent_rate_mhz * m + \
(parent_rate_mhz * frac >> 12)) * 2 / n;
rate_mhz = rate_mhz >> od >> od2;
} else
rate_mhz = (parent_rate_mhz * m / n) >> od >> od2;
return rate_mhz * 1000000;
}
static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
struct meson_clk_pll *pll = to_meson_clk_pll(hw);
const struct pll_rate_table *rate_table = pll->rate_table;
int i;
for (i = 0; i < pll->rate_count; i++) {
if (rate <= rate_table[i].rate)
return rate_table[i].rate;
}
/* else return the smallest value */
return rate_table[0].rate;
}
static const struct pll_rate_table *meson_clk_get_pll_settings(struct meson_clk_pll *pll,
unsigned long rate)
{
const struct pll_rate_table *rate_table = pll->rate_table;
int i;
for (i = 0; i < pll->rate_count; i++) {
if (rate == rate_table[i].rate)
return &rate_table[i];
}
return NULL;
}
static int meson_clk_pll_wait_lock(struct meson_clk_pll *pll,
struct parm *p_n)
{
int delay = 24000000;
u32 reg;
while (delay > 0) {
reg = readl(pll->base + p_n->reg_off);
if (reg & MESON_PLL_LOCK)
return 0;
delay--;
}
return -ETIMEDOUT;
}
static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct meson_clk_pll *pll = to_meson_clk_pll(hw);
struct parm *p;
const struct pll_rate_table *rate_set;
unsigned long old_rate;
int ret = 0;
u32 reg;
if (parent_rate == 0 || rate == 0)
return -EINVAL;
old_rate = rate;
rate_set = meson_clk_get_pll_settings(pll, rate);
if (!rate_set)
return -EINVAL;
/* PLL reset */
p = &pll->n;
reg = readl(pll->base + p->reg_off);
writel(reg | MESON_PLL_RESET, pll->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, rate_set->n);
writel(reg, pll->base + p->reg_off);
p = &pll->m;
reg = readl(pll->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, rate_set->m);
writel(reg, pll->base + p->reg_off);
p = &pll->od;
reg = readl(pll->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, rate_set->od);
writel(reg, pll->base + p->reg_off);
p = &pll->od2;
if (p->width) {
reg = readl(pll->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, rate_set->od2);
writel(reg, pll->base + p->reg_off);
}
p = &pll->frac;
if (p->width) {
reg = readl(pll->base + p->reg_off);
reg = PARM_SET(p->width, p->shift, reg, rate_set->frac);
writel(reg, pll->base + p->reg_off);
}
p = &pll->n;
ret = meson_clk_pll_wait_lock(pll, p);
if (ret) {
pr_warn("%s: pll did not lock, trying to restore old rate %lu\n",
__func__, old_rate);
meson_clk_pll_set_rate(hw, old_rate, parent_rate);
}
return ret;
}
const struct clk_ops meson_clk_pll_ops = {
.recalc_rate = meson_clk_pll_recalc_rate,
.round_rate = meson_clk_pll_round_rate,
.set_rate = meson_clk_pll_set_rate,
};
const struct clk_ops meson_clk_pll_ro_ops = {
.recalc_rate = meson_clk_pll_recalc_rate,
};
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