linux/drivers/pwm/pwm-meson.c
Uwe Kleine-König 71523d1812 pwm: Ensure pwm_apply_state() doesn't modify the state argument
It is surprising for a PWM consumer when the variable holding the
requested state is modified by pwm_apply_state(). Consider for example a
driver doing:

        #define PERIOD 5000000
        #define DUTY_LITTLE 10
        ...
        struct pwm_state state = {
                .period = PERIOD,
                .duty_cycle = DUTY_LITTLE,
                .polarity = PWM_POLARITY_NORMAL,
                .enabled = true,
        };

        pwm_apply_state(mypwm, &state);
        ...
        state.duty_cycle = PERIOD / 2;
        pwm_apply_state(mypwm, &state);

For sure the second call to pwm_apply_state() should still have
state.period = PERIOD and not something the hardware driver chose for a
reason that doesn't necessarily apply to the second call.

So declare the state argument as a pointer to a const type and adapt all
drivers' .apply callbacks.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-09-21 03:25:10 +02:00

597 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
* PWM controller driver for Amlogic Meson SoCs.
*
* This PWM is only a set of Gates, Dividers and Counters:
* PWM output is achieved by calculating a clock that permits calculating
* two periods (low and high). The counter then has to be set to switch after
* N cycles for the first half period.
* The hardware has no "polarity" setting. This driver reverses the period
* cycles (the low length is inverted with the high length) for
* PWM_POLARITY_INVERSED. This means that .get_state cannot read the polarity
* from the hardware.
* Setting the duty cycle will disable and re-enable the PWM output.
* Disabling the PWM stops the output immediately (without waiting for the
* current period to complete first).
*
* The public S912 (GXM) datasheet contains some documentation for this PWM
* controller starting on page 543:
* https://dl.khadas.com/Hardware/VIM2/Datasheet/S912_Datasheet_V0.220170314publicversion-Wesion.pdf
* An updated version of this IP block is found in S922X (G12B) SoCs. The
* datasheet contains the description for this IP block revision starting at
* page 1084:
* https://dn.odroid.com/S922X/ODROID-N2/Datasheet/S922X_Public_Datasheet_V0.2.pdf
*
* Copyright (c) 2016 BayLibre, SAS.
* Author: Neil Armstrong <narmstrong@baylibre.com>
* Copyright (C) 2014 Amlogic, Inc.
*/
#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#define REG_PWM_A 0x0
#define REG_PWM_B 0x4
#define PWM_LOW_MASK GENMASK(15, 0)
#define PWM_HIGH_MASK GENMASK(31, 16)
#define REG_MISC_AB 0x8
#define MISC_B_CLK_EN BIT(23)
#define MISC_A_CLK_EN BIT(15)
#define MISC_CLK_DIV_MASK 0x7f
#define MISC_B_CLK_DIV_SHIFT 16
#define MISC_A_CLK_DIV_SHIFT 8
#define MISC_B_CLK_SEL_SHIFT 6
#define MISC_A_CLK_SEL_SHIFT 4
#define MISC_CLK_SEL_MASK 0x3
#define MISC_B_EN BIT(1)
#define MISC_A_EN BIT(0)
#define MESON_NUM_PWMS 2
static struct meson_pwm_channel_data {
u8 reg_offset;
u8 clk_sel_shift;
u8 clk_div_shift;
u32 clk_en_mask;
u32 pwm_en_mask;
} meson_pwm_per_channel_data[MESON_NUM_PWMS] = {
{
.reg_offset = REG_PWM_A,
.clk_sel_shift = MISC_A_CLK_SEL_SHIFT,
.clk_div_shift = MISC_A_CLK_DIV_SHIFT,
.clk_en_mask = MISC_A_CLK_EN,
.pwm_en_mask = MISC_A_EN,
},
{
.reg_offset = REG_PWM_B,
.clk_sel_shift = MISC_B_CLK_SEL_SHIFT,
.clk_div_shift = MISC_B_CLK_DIV_SHIFT,
.clk_en_mask = MISC_B_CLK_EN,
.pwm_en_mask = MISC_B_EN,
}
};
struct meson_pwm_channel {
unsigned int hi;
unsigned int lo;
u8 pre_div;
struct clk *clk_parent;
struct clk_mux mux;
struct clk *clk;
};
struct meson_pwm_data {
const char * const *parent_names;
unsigned int num_parents;
};
struct meson_pwm {
struct pwm_chip chip;
const struct meson_pwm_data *data;
struct meson_pwm_channel channels[MESON_NUM_PWMS];
void __iomem *base;
/*
* Protects register (write) access to the REG_MISC_AB register
* that is shared between the two PWMs.
*/
spinlock_t lock;
};
static inline struct meson_pwm *to_meson_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct meson_pwm, chip);
}
static int meson_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct meson_pwm *meson = to_meson_pwm(chip);
struct meson_pwm_channel *channel;
struct device *dev = chip->dev;
int err;
channel = pwm_get_chip_data(pwm);
if (channel)
return 0;
channel = &meson->channels[pwm->hwpwm];
if (channel->clk_parent) {
err = clk_set_parent(channel->clk, channel->clk_parent);
if (err < 0) {
dev_err(dev, "failed to set parent %s for %s: %d\n",
__clk_get_name(channel->clk_parent),
__clk_get_name(channel->clk), err);
return err;
}
}
err = clk_prepare_enable(channel->clk);
if (err < 0) {
dev_err(dev, "failed to enable clock %s: %d\n",
__clk_get_name(channel->clk), err);
return err;
}
return pwm_set_chip_data(pwm, channel);
}
static void meson_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
if (channel)
clk_disable_unprepare(channel->clk);
}
static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
unsigned int duty, period, pre_div, cnt, duty_cnt;
unsigned long fin_freq = -1;
duty = state->duty_cycle;
period = state->period;
if (state->polarity == PWM_POLARITY_INVERSED)
duty = period - duty;
fin_freq = clk_get_rate(channel->clk);
if (fin_freq == 0) {
dev_err(meson->chip.dev, "invalid source clock frequency\n");
return -EINVAL;
}
dev_dbg(meson->chip.dev, "fin_freq: %lu Hz\n", fin_freq);
pre_div = div64_u64(fin_freq * (u64)period, NSEC_PER_SEC * 0xffffLL);
if (pre_div > MISC_CLK_DIV_MASK) {
dev_err(meson->chip.dev, "unable to get period pre_div\n");
return -EINVAL;
}
cnt = div64_u64(fin_freq * (u64)period, NSEC_PER_SEC * (pre_div + 1));
if (cnt > 0xffff) {
dev_err(meson->chip.dev, "unable to get period cnt\n");
return -EINVAL;
}
dev_dbg(meson->chip.dev, "period=%u pre_div=%u cnt=%u\n", period,
pre_div, cnt);
if (duty == period) {
channel->pre_div = pre_div;
channel->hi = cnt;
channel->lo = 0;
} else if (duty == 0) {
channel->pre_div = pre_div;
channel->hi = 0;
channel->lo = cnt;
} else {
/* Then check is we can have the duty with the same pre_div */
duty_cnt = div64_u64(fin_freq * (u64)duty,
NSEC_PER_SEC * (pre_div + 1));
if (duty_cnt > 0xffff) {
dev_err(meson->chip.dev, "unable to get duty cycle\n");
return -EINVAL;
}
dev_dbg(meson->chip.dev, "duty=%u pre_div=%u duty_cnt=%u\n",
duty, pre_div, duty_cnt);
channel->pre_div = pre_div;
channel->hi = duty_cnt;
channel->lo = cnt - duty_cnt;
}
return 0;
}
static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
{
struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
struct meson_pwm_channel_data *channel_data;
unsigned long flags;
u32 value;
channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
spin_lock_irqsave(&meson->lock, flags);
value = readl(meson->base + REG_MISC_AB);
value &= ~(MISC_CLK_DIV_MASK << channel_data->clk_div_shift);
value |= channel->pre_div << channel_data->clk_div_shift;
value |= channel_data->clk_en_mask;
writel(value, meson->base + REG_MISC_AB);
value = FIELD_PREP(PWM_HIGH_MASK, channel->hi) |
FIELD_PREP(PWM_LOW_MASK, channel->lo);
writel(value, meson->base + channel_data->reg_offset);
value = readl(meson->base + REG_MISC_AB);
value |= channel_data->pwm_en_mask;
writel(value, meson->base + REG_MISC_AB);
spin_unlock_irqrestore(&meson->lock, flags);
}
static void meson_pwm_disable(struct meson_pwm *meson, struct pwm_device *pwm)
{
unsigned long flags;
u32 value;
spin_lock_irqsave(&meson->lock, flags);
value = readl(meson->base + REG_MISC_AB);
value &= ~meson_pwm_per_channel_data[pwm->hwpwm].pwm_en_mask;
writel(value, meson->base + REG_MISC_AB);
spin_unlock_irqrestore(&meson->lock, flags);
}
static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct meson_pwm_channel *channel = pwm_get_chip_data(pwm);
struct meson_pwm *meson = to_meson_pwm(chip);
int err = 0;
if (!state)
return -EINVAL;
if (!state->enabled) {
if (state->polarity == PWM_POLARITY_INVERSED) {
/*
* This IP block revision doesn't have an "always high"
* setting which we can use for "inverted disabled".
* Instead we achieve this using the same settings
* that we use a pre_div of 0 (to get the shortest
* possible duration for one "count") and
* "period == duty_cycle". This results in a signal
* which is LOW for one "count", while being HIGH for
* the rest of the (so the signal is HIGH for slightly
* less than 100% of the period, but this is the best
* we can achieve).
*/
channel->pre_div = 0;
channel->hi = ~0;
channel->lo = 0;
meson_pwm_enable(meson, pwm);
} else {
meson_pwm_disable(meson, pwm);
}
} else {
err = meson_pwm_calc(meson, pwm, state);
if (err < 0)
return err;
meson_pwm_enable(meson, pwm);
}
return 0;
}
static unsigned int meson_pwm_cnt_to_ns(struct pwm_chip *chip,
struct pwm_device *pwm, u32 cnt)
{
struct meson_pwm *meson = to_meson_pwm(chip);
struct meson_pwm_channel *channel;
unsigned long fin_freq;
u32 fin_ns;
/* to_meson_pwm() can only be used after .get_state() is called */
channel = &meson->channels[pwm->hwpwm];
fin_freq = clk_get_rate(channel->clk);
if (fin_freq == 0)
return 0;
fin_ns = div_u64(NSEC_PER_SEC, fin_freq);
return cnt * fin_ns * (channel->pre_div + 1);
}
static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct meson_pwm *meson = to_meson_pwm(chip);
struct meson_pwm_channel_data *channel_data;
struct meson_pwm_channel *channel;
u32 value, tmp;
if (!state)
return;
channel = &meson->channels[pwm->hwpwm];
channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
value = readl(meson->base + REG_MISC_AB);
tmp = channel_data->pwm_en_mask | channel_data->clk_en_mask;
state->enabled = (value & tmp) == tmp;
tmp = value >> channel_data->clk_div_shift;
channel->pre_div = FIELD_GET(MISC_CLK_DIV_MASK, tmp);
value = readl(meson->base + channel_data->reg_offset);
channel->lo = FIELD_GET(PWM_LOW_MASK, value);
channel->hi = FIELD_GET(PWM_HIGH_MASK, value);
if (channel->lo == 0) {
state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
state->duty_cycle = state->period;
} else if (channel->lo >= channel->hi) {
state->period = meson_pwm_cnt_to_ns(chip, pwm,
channel->lo + channel->hi);
state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm,
channel->hi);
} else {
state->period = 0;
state->duty_cycle = 0;
}
}
static const struct pwm_ops meson_pwm_ops = {
.request = meson_pwm_request,
.free = meson_pwm_free,
.apply = meson_pwm_apply,
.get_state = meson_pwm_get_state,
.owner = THIS_MODULE,
};
static const char * const pwm_meson8b_parent_names[] = {
"xtal", "vid_pll", "fclk_div4", "fclk_div3"
};
static const struct meson_pwm_data pwm_meson8b_data = {
.parent_names = pwm_meson8b_parent_names,
.num_parents = ARRAY_SIZE(pwm_meson8b_parent_names),
};
static const char * const pwm_gxbb_parent_names[] = {
"xtal", "hdmi_pll", "fclk_div4", "fclk_div3"
};
static const struct meson_pwm_data pwm_gxbb_data = {
.parent_names = pwm_gxbb_parent_names,
.num_parents = ARRAY_SIZE(pwm_gxbb_parent_names),
};
/*
* Only the 2 first inputs of the GXBB AO PWMs are valid
* The last 2 are grounded
*/
static const char * const pwm_gxbb_ao_parent_names[] = {
"xtal", "clk81"
};
static const struct meson_pwm_data pwm_gxbb_ao_data = {
.parent_names = pwm_gxbb_ao_parent_names,
.num_parents = ARRAY_SIZE(pwm_gxbb_ao_parent_names),
};
static const char * const pwm_axg_ee_parent_names[] = {
"xtal", "fclk_div5", "fclk_div4", "fclk_div3"
};
static const struct meson_pwm_data pwm_axg_ee_data = {
.parent_names = pwm_axg_ee_parent_names,
.num_parents = ARRAY_SIZE(pwm_axg_ee_parent_names),
};
static const char * const pwm_axg_ao_parent_names[] = {
"aoclk81", "xtal", "fclk_div4", "fclk_div5"
};
static const struct meson_pwm_data pwm_axg_ao_data = {
.parent_names = pwm_axg_ao_parent_names,
.num_parents = ARRAY_SIZE(pwm_axg_ao_parent_names),
};
static const char * const pwm_g12a_ao_ab_parent_names[] = {
"xtal", "aoclk81", "fclk_div4", "fclk_div5"
};
static const struct meson_pwm_data pwm_g12a_ao_ab_data = {
.parent_names = pwm_g12a_ao_ab_parent_names,
.num_parents = ARRAY_SIZE(pwm_g12a_ao_ab_parent_names),
};
static const char * const pwm_g12a_ao_cd_parent_names[] = {
"xtal", "aoclk81",
};
static const struct meson_pwm_data pwm_g12a_ao_cd_data = {
.parent_names = pwm_g12a_ao_cd_parent_names,
.num_parents = ARRAY_SIZE(pwm_g12a_ao_cd_parent_names),
};
static const char * const pwm_g12a_ee_parent_names[] = {
"xtal", "hdmi_pll", "fclk_div4", "fclk_div3"
};
static const struct meson_pwm_data pwm_g12a_ee_data = {
.parent_names = pwm_g12a_ee_parent_names,
.num_parents = ARRAY_SIZE(pwm_g12a_ee_parent_names),
};
static const struct of_device_id meson_pwm_matches[] = {
{
.compatible = "amlogic,meson8b-pwm",
.data = &pwm_meson8b_data
},
{
.compatible = "amlogic,meson-gxbb-pwm",
.data = &pwm_gxbb_data
},
{
.compatible = "amlogic,meson-gxbb-ao-pwm",
.data = &pwm_gxbb_ao_data
},
{
.compatible = "amlogic,meson-axg-ee-pwm",
.data = &pwm_axg_ee_data
},
{
.compatible = "amlogic,meson-axg-ao-pwm",
.data = &pwm_axg_ao_data
},
{
.compatible = "amlogic,meson-g12a-ee-pwm",
.data = &pwm_g12a_ee_data
},
{
.compatible = "amlogic,meson-g12a-ao-pwm-ab",
.data = &pwm_g12a_ao_ab_data
},
{
.compatible = "amlogic,meson-g12a-ao-pwm-cd",
.data = &pwm_g12a_ao_cd_data
},
{},
};
MODULE_DEVICE_TABLE(of, meson_pwm_matches);
static int meson_pwm_init_channels(struct meson_pwm *meson)
{
struct device *dev = meson->chip.dev;
struct clk_init_data init;
unsigned int i;
char name[255];
int err;
for (i = 0; i < meson->chip.npwm; i++) {
struct meson_pwm_channel *channel = &meson->channels[i];
snprintf(name, sizeof(name), "%s#mux%u", dev_name(dev), i);
init.name = name;
init.ops = &clk_mux_ops;
init.flags = 0;
init.parent_names = meson->data->parent_names;
init.num_parents = meson->data->num_parents;
channel->mux.reg = meson->base + REG_MISC_AB;
channel->mux.shift =
meson_pwm_per_channel_data[i].clk_sel_shift;
channel->mux.mask = MISC_CLK_SEL_MASK;
channel->mux.flags = 0;
channel->mux.lock = &meson->lock;
channel->mux.table = NULL;
channel->mux.hw.init = &init;
channel->clk = devm_clk_register(dev, &channel->mux.hw);
if (IS_ERR(channel->clk)) {
err = PTR_ERR(channel->clk);
dev_err(dev, "failed to register %s: %d\n", name, err);
return err;
}
snprintf(name, sizeof(name), "clkin%u", i);
channel->clk_parent = devm_clk_get_optional(dev, name);
if (IS_ERR(channel->clk_parent))
return PTR_ERR(channel->clk_parent);
}
return 0;
}
static int meson_pwm_probe(struct platform_device *pdev)
{
struct meson_pwm *meson;
struct resource *regs;
int err;
meson = devm_kzalloc(&pdev->dev, sizeof(*meson), GFP_KERNEL);
if (!meson)
return -ENOMEM;
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
meson->base = devm_ioremap_resource(&pdev->dev, regs);
if (IS_ERR(meson->base))
return PTR_ERR(meson->base);
spin_lock_init(&meson->lock);
meson->chip.dev = &pdev->dev;
meson->chip.ops = &meson_pwm_ops;
meson->chip.base = -1;
meson->chip.npwm = MESON_NUM_PWMS;
meson->chip.of_xlate = of_pwm_xlate_with_flags;
meson->chip.of_pwm_n_cells = 3;
meson->data = of_device_get_match_data(&pdev->dev);
err = meson_pwm_init_channels(meson);
if (err < 0)
return err;
err = pwmchip_add(&meson->chip);
if (err < 0) {
dev_err(&pdev->dev, "failed to register PWM chip: %d\n", err);
return err;
}
platform_set_drvdata(pdev, meson);
return 0;
}
static int meson_pwm_remove(struct platform_device *pdev)
{
struct meson_pwm *meson = platform_get_drvdata(pdev);
return pwmchip_remove(&meson->chip);
}
static struct platform_driver meson_pwm_driver = {
.driver = {
.name = "meson-pwm",
.of_match_table = meson_pwm_matches,
},
.probe = meson_pwm_probe,
.remove = meson_pwm_remove,
};
module_platform_driver(meson_pwm_driver);
MODULE_DESCRIPTION("Amlogic Meson PWM Generator driver");
MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
MODULE_LICENSE("Dual BSD/GPL");