linux/drivers/clk/meson/clk-pll.c

228 lines
5.6 KiB
C

/*
* 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)
struct meson_clk_pll {
struct clk_hw hw;
void __iomem *base;
struct pll_conf *conf;
unsigned int rate_count;
spinlock_t *lock;
};
#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, od;
u32 reg;
p = &pll->conf->n;
reg = readl(pll->base + p->reg_off);
n = PARM_GET(p->width, p->shift, reg);
p = &pll->conf->m;
reg = readl(pll->base + p->reg_off);
m = PARM_GET(p->width, p->shift, reg);
p = &pll->conf->od;
reg = readl(pll->base + p->reg_off);
od = PARM_GET(p->width, p->shift, reg);
rate_mhz = (parent_rate_mhz * m / n) >> od;
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->conf->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->conf->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->conf->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->conf->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->conf->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->conf->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;
}
static 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,
};
static const struct clk_ops meson_clk_pll_ro_ops = {
.recalc_rate = meson_clk_pll_recalc_rate,
};
struct clk *meson_clk_register_pll(const struct clk_conf *clk_conf,
void __iomem *reg_base,
spinlock_t *lock)
{
struct clk *clk;
struct meson_clk_pll *clk_pll;
struct clk_init_data init;
clk_pll = kzalloc(sizeof(*clk_pll), GFP_KERNEL);
if (!clk_pll)
return ERR_PTR(-ENOMEM);
clk_pll->base = reg_base + clk_conf->reg_off;
clk_pll->lock = lock;
clk_pll->conf = clk_conf->conf.pll;
init.name = clk_conf->clk_name;
init.flags = clk_conf->flags | CLK_GET_RATE_NOCACHE;
init.parent_names = &clk_conf->clks_parent[0];
init.num_parents = 1;
init.ops = &meson_clk_pll_ro_ops;
/* If no rate_table is specified we assume the PLL is read-only */
if (clk_pll->conf->rate_table) {
int len;
for (len = 0; clk_pll->conf->rate_table[len].rate != 0; )
len++;
clk_pll->rate_count = len;
init.ops = &meson_clk_pll_ops;
}
clk_pll->hw.init = &init;
clk = clk_register(NULL, &clk_pll->hw);
if (IS_ERR(clk))
kfree(clk_pll);
return clk;
}