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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2020 SiFive, Inc
* For SiFive's PWM IP block documentation please refer Chapter 14 of
* Reference Manual : https://static.dev.sifive.com/FU540-C000-v1.0.pdf
*
* Limitations:
* - When changing both duty cycle and period, we cannot prevent in
* software that the output might produce a period with mixed
* settings (new period length and old duty cycle).
* - The hardware cannot generate a 100% duty cycle.
* - The hardware generates only inverted output.
*/
#include <common.h>
#include <clk.h>
#include <div64.h>
#include <dm.h>
#include <pwm.h>
#include <regmap.h>
#include <linux/io.h>
#include <linux/log2.h>
#include <linux/bitfield.h>
/* PWMCFG fields */
#define PWM_SIFIVE_PWMCFG_SCALE GENMASK(3, 0)
#define PWM_SIFIVE_PWMCFG_STICKY BIT(8)
#define PWM_SIFIVE_PWMCFG_ZERO_CMP BIT(9)
#define PWM_SIFIVE_PWMCFG_DEGLITCH BIT(10)
#define PWM_SIFIVE_PWMCFG_EN_ALWAYS BIT(12)
#define PWM_SIFIVE_PWMCFG_EN_ONCE BIT(13)
#define PWM_SIFIVE_PWMCFG_CENTER BIT(16)
#define PWM_SIFIVE_PWMCFG_GANG BIT(24)
#define PWM_SIFIVE_PWMCFG_IP BIT(28)
/* PWM_SIFIVE_SIZE_PWMCMP is used to calculate offset for pwmcmpX registers */
#define PWM_SIFIVE_SIZE_PWMCMP 4
#define PWM_SIFIVE_CMPWIDTH 16
DECLARE_GLOBAL_DATA_PTR;
struct pwm_sifive_regs {
unsigned long cfg;
unsigned long cnt;
unsigned long pwms;
unsigned long cmp0;
};
struct pwm_sifive_data {
struct pwm_sifive_regs regs;
};
struct pwm_sifive_priv {
void __iomem *base;
ulong freq;
const struct pwm_sifive_data *data;
};
static int pwm_sifive_set_config(struct udevice *dev, uint channel,
uint period_ns, uint duty_ns)
{
struct pwm_sifive_priv *priv = dev_get_priv(dev);
const struct pwm_sifive_regs *regs = &priv->data->regs;
unsigned long scale_pow;
unsigned long long num;
u32 scale, val = 0, frac;
debug("%s: period_ns=%u, duty_ns=%u\n", __func__, period_ns, duty_ns);
/*
* The PWM unit is used with pwmzerocmp=0, so the only way to modify the
* period length is using pwmscale which provides the number of bits the
* counter is shifted before being feed to the comparators. A period
* lasts (1 << (PWM_SIFIVE_CMPWIDTH + pwmscale)) clock ticks.
* (1 << (PWM_SIFIVE_CMPWIDTH + scale)) * 10^9/rate = period
*/
scale_pow = lldiv((uint64_t)priv->freq * period_ns, 1000000000);
scale = clamp(ilog2(scale_pow) - PWM_SIFIVE_CMPWIDTH, 0, 0xf);
val |= FIELD_PREP(PWM_SIFIVE_PWMCFG_SCALE, scale);
/*
* The problem of output producing mixed setting as mentioned at top,
* occurs here. To minimize the window for this problem, we are
* calculating the register values first and then writing them
* consecutively
*/
num = (u64)duty_ns * (1U << PWM_SIFIVE_CMPWIDTH);
frac = DIV_ROUND_CLOSEST_ULL(num, period_ns);
frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
writel(val, priv->base + regs->cfg);
writel(frac, priv->base + regs->cmp0 + channel *
PWM_SIFIVE_SIZE_PWMCMP);
return 0;
}
static int pwm_sifive_set_enable(struct udevice *dev, uint channel, bool enable)
{
struct pwm_sifive_priv *priv = dev_get_priv(dev);
const struct pwm_sifive_regs *regs = &priv->data->regs;
u32 val;
debug("%s: Enable '%s'\n", __func__, dev->name);
if (enable) {
val = readl(priv->base + regs->cfg);
val |= PWM_SIFIVE_PWMCFG_EN_ALWAYS;
writel(val, priv->base + regs->cfg);
} else {
writel(0, priv->base + regs->cmp0 + channel *
PWM_SIFIVE_SIZE_PWMCMP);
}
return 0;
}
static int pwm_sifive_of_to_plat(struct udevice *dev)
{
struct pwm_sifive_priv *priv = dev_get_priv(dev);
priv->base = dev_read_addr_ptr(dev);
return 0;
}
static int pwm_sifive_probe(struct udevice *dev)
{
struct pwm_sifive_priv *priv = dev_get_priv(dev);
struct clk clk;
int ret = 0;
ret = clk_get_by_index(dev, 0, &clk);
if (ret < 0) {
debug("%s get clock fail!\n", __func__);
return -EINVAL;
}
priv->freq = clk_get_rate(&clk);
priv->data = (struct pwm_sifive_data *)dev_get_driver_data(dev);
return 0;
}
static const struct pwm_ops pwm_sifive_ops = {
.set_config = pwm_sifive_set_config,
.set_enable = pwm_sifive_set_enable,
};
static const struct pwm_sifive_data pwm_data = {
.regs = {
.cfg = 0x00,
.cnt = 0x08,
.pwms = 0x10,
.cmp0 = 0x20,
},
};
static const struct udevice_id pwm_sifive_ids[] = {
{ .compatible = "sifive,pwm0", .data = (ulong)&pwm_data},
{ }
};
U_BOOT_DRIVER(pwm_sifive) = {
.name = "pwm_sifive",
.id = UCLASS_PWM,
.of_match = pwm_sifive_ids,
.ops = &pwm_sifive_ops,
.of_to_plat = pwm_sifive_of_to_plat,
.probe = pwm_sifive_probe,
.priv_auto = sizeof(struct pwm_sifive_priv),
};
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