[PATCH RFC 3/4] pwm: sunxi: Add support Allwinner D1 PWM
John Watts
contact at jookia.org
Tue May 21 01:37:02 CEST 2024
On Sat, May 18, 2024 at 01:54:45PM +1000, John Watts wrote:
> This driver documents and handles setting up PWM on the D1.
>
> Signed-off-by: John Watts <contact at jookia.org>
> ---
> drivers/pwm/Kconfig | 6 +
> drivers/pwm/Makefile | 1 +
> drivers/pwm/sunxi_pwm_d1.c | 542 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 549 insertions(+)
Patch v9 of the kernel uses apb now instead of apb0, so this should be changed
to fit once the kernel driver is merged.
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 6e79868d0e..8c4c910ea7 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -112,6 +112,12 @@ config PWM_SUNXI
> This PWM is found on H3, A64 and other Allwinner SoCs. It supports a
> programmable period and duty cycle. A 16-bit counter is used.
>
> +config PWM_SUNXI_D1
> + bool "Enable support for the Allwinner D1 Sunxi PWM"
> + depends on DM_PWM
> + help
> + This PWM is found on D1, T113-S3 and R329 SoCs.
> +
> config PWM_TI_EHRPWM
> bool "Enable support for EHRPWM PWM"
> depends on DM_PWM && ARCH_OMAP2PLUS
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index e4d10c8dc3..ea96e7159b 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -23,4 +23,5 @@ obj-$(CONFIG_PWM_SANDBOX) += sandbox_pwm.o
> obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o
> obj-$(CONFIG_PWM_TEGRA) += tegra_pwm.o
> obj-$(CONFIG_PWM_SUNXI) += sunxi_pwm.o
> +obj-$(CONFIG_PWM_SUNXI_D1) += sunxi_pwm_d1.o
> obj-$(CONFIG_PWM_TI_EHRPWM) += pwm-ti-ehrpwm.o
> diff --git a/drivers/pwm/sunxi_pwm_d1.c b/drivers/pwm/sunxi_pwm_d1.c
> new file mode 100644
> index 0000000000..6c57bc6e85
> --- /dev/null
> +++ b/drivers/pwm/sunxi_pwm_d1.c
> @@ -0,0 +1,542 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright 2022 Jookia <contact at jookia.org>
> +/*
> + * The Allwinner D1's PWM channels are 16-bit counters with up to
> + * 65537 cycles (yes, you read that correctly).
> + *
> + * Each channel must be programmed using three variables:
> + * - The entire cycle count (used for the period)
> + * - The active cycle count (the count of inactive cycles)
> + * - The polarity (specifies if the signal is active high or low)
> + * The cycle counts are at minimum 1 and at maximum 65536.
> + *
> + * The controller will output the number of entire cycles plus one
> + * extra, with any cycles after the active cycle output as active.
> + *
> + * Consider a PWM period of 128 nanoseconds and a cycle period of 32.
> + * Setting the entire cycle count to 3 and active cycle count to 4
> + * gives an output like so:
> + *
> + * - Cycle 1 runs 0 to 32 nanoseconds, inactive
> + * - Cycle 2 runs 32 to 64 nanoseconds, inactive
> + * - Cycle 3 runs 64 to 96 nanoseconds, inactive
> + * - Cycle 4 runs 96 to 128 nanoseconds, inactive
> + * - Cycle 5 is skipped but would run 128 to 160 nanoseconds, active
> + *
> + * If we set the entire count to 4, cycle 5 would run and we wouldn't be
> + * able to specify it as inactive as the active count only goes up to 4.
> + *
> + * In practice this means we want to set the entire cycle to be one less
> + * then the actual number of cycles we want, so we can set the number of
> + * active cycles to be up to maximum for a fully inactive signal.
> + *
> + * The PWM channels are paired and clocked together, resulting in a
> + * cycle time found using the following formula:
> + *
> + * PWM0_CYCLE_NS = 1000000000 / (BUS_CLOCK / COMMON_DIV / PWM0_PRESCALER_K)
> + * PWM1_CYCLE_NS = 1000000000 / (BUS_CLOCK / COMMON_DIV / PWM1_PRESCALER_K)
> + *
> + * This means both clocks should ideally be set at the same time and not
> + * impact each other too much.
> + */
> +
> +#include <dm.h>
> +#include <dm/device_compat.h>
> +#include <dm/devres.h>
> +#include <clk.h>
> +#include <reset.h>
> +#include <pwm.h>
> +#include <asm/io.h>
> +
> +/* PWM channel information */
> +struct pwm_channel {
> + uint period_ns;
> + uint duty_ns;
> + bool polarity;
> + bool enable;
> + bool updated;
> +};
> +
> +/* Timings found for a PWM channel */
> +struct pwm_timings {
> + uint cycle_ns;
> + uint period_ns;
> + uint duty_ns;
> + uint clock_id;
> + uint common_div;
> + uint prescale_k;
> + uint entire_cycles;
> + uint active_cycles;
> + uint polarity;
> +};
> +
> +/* Driver state */
> +struct sunxi_pwm_d1_priv {
> + void *base;
> + struct clk *clk_bus;
> + struct clk *clk_srcs[3]; /* Last value must be NULL */
> + struct reset_ctl *reset;
> + int npwm;
> + struct pwm_channel *channels;
> +};
> +
> +/* Divides a nanosecond value, rounding up for very low values */
> +uint div_ns(uint ns, uint div)
> +{
> + uint result = (ns / div);
> +
> + /* If the number is less than 1000, round it to the nearest digit */
> + if (result < 1000)
> + result = (ns + (div - 1)) / div;
> +
> + if (result < 1)
> + result = 1;
> +
> + return result;
> +}
> +
> +/* Checks if an error is relatively too large */
> +int error_too_large(uint actual, uint target)
> +{
> + /* For a target of zero we want zero */
> + if (target == 0)
> + return (actual == 0);
> +
> + /* Don't overflow large numbers when we multiply by 100 */
> + while (actual > 1000) {
> + actual /= 100;
> + target /= 100;
> + }
> +
> + int error_percent = (actual * 100) / target;
> +
> + return (error_percent < 80 || 120 < error_percent);
> +}
> +
> +/* Calculates the cycle nanoseconds from clock parameters */
> +int get_cycle_ns(uint parent_hz, uint common_div, uint prescaler)
> +{
> + return 1000000000 / ((parent_hz / common_div) / prescaler);
> +}
> +
> +int find_channel_dividers(uint period_ns,
> + uint parent_hz,
> + struct pwm_timings *out)
> +{
> + uint ideal_cycle_ns = div_ns(period_ns, 65536);
> + int common_div = out->common_div;
> + int prescaler = 1;
> + uint cycle_ns = 0;
> +
> + for (;;) {
> + cycle_ns = get_cycle_ns(parent_hz, common_div, prescaler);
> + if (cycle_ns >= ideal_cycle_ns)
> + break;
> +
> + prescaler *= 2;
> + if (prescaler > 256) {
> + if (common_div < 256) {
> + prescaler = 1;
> + common_div *= 2;
> + } else {
> + return -1;
> + }
> + }
> + }
> +
> + out->common_div = common_div;
> + out->prescale_k = prescaler;
> + out->cycle_ns = cycle_ns;
> +
> + return 0;
> +}
> +
> +int find_channel_timings(const struct pwm_channel *in,
> + struct pwm_timings *out,
> + uint parent_hz)
> +{
> + struct pwm_timings new = *out;
> +
> + if (find_channel_dividers(in->period_ns, parent_hz, &new))
> + return -1;
> +
> + new.entire_cycles = (in->period_ns / new.cycle_ns) - 1;
> + new.active_cycles = (in->duty_ns / new.cycle_ns);
> + new.period_ns = (new.entire_cycles + 1) * new.cycle_ns;
> + new.duty_ns = new.active_cycles * new.cycle_ns;
> + new.polarity = in->polarity;
> +
> + if (error_too_large(new.period_ns, in->period_ns))
> + return -1;
> +
> + if (in->duty_ns && error_too_large(new.duty_ns, in->duty_ns))
> + return -1;
> +
> + *out = new;
> +
> + return 0;
> +}
> +
> +int find_pair_timings(const struct pwm_channel *channel0,
> + const struct pwm_channel *channel1,
> + struct pwm_timings *timings0,
> + struct pwm_timings *timings1,
> + int clock_hz)
> +{
> + struct pwm_timings new0 = *timings0;
> + struct pwm_timings new1 = *timings1;
> + int err0 = 0;
> + int err1 = 0;
> +
> + new0.common_div = 1;
> + new1.common_div = 1;
> +
> + if (channel0->enable) {
> + err0 = find_channel_timings(channel0, &new0, clock_hz);
> + new1.common_div = new0.common_div;
> + }
> +
> + if (channel1->enable) {
> + err1 = find_channel_timings(channel1, &new1, clock_hz);
> + new0 = *timings0;
> + new0.common_div = new1.common_div;
> + }
> +
> + if (channel0->enable && channel1->enable) {
> + err0 = find_channel_timings(channel0, &new0, clock_hz);
> +
> + if (new0.common_div != new1.common_div)
> + return -1;
> + }
> +
> + if (err0 || err1)
> + return -1;
> +
> + *timings0 = new0;
> + *timings1 = new1;
> +
> + return 0;
> +}
> +
> +int find_pair_timings_clocked(struct clk **clk_srcs,
> + const struct pwm_channel *channel0,
> + const struct pwm_channel *channel1,
> + struct pwm_timings *timings0,
> + struct pwm_timings *timings1)
> +{
> + struct clk *clock = *clk_srcs;
> +
> + for (int clock_id = 0; clock; clock = clk_srcs[++clock_id]) {
> + int clock_hz = clk_get_rate(clock);
> +
> + if (clock_hz == 0 || IS_ERR_VALUE(clock_hz))
> + continue;
> +
> + timings0->clock_id = clock_id;
> + timings1->clock_id = clock_id;
> +
> + if (find_pair_timings(channel0, channel1,
> + timings0, timings1,
> + clock_hz))
> + continue;
> +
> + return 0;
> + }
> +
> + return -1;
> +}
> +
> +#define PCGR(base) ((base) + 0x40)
> +#define PCGR_CLK_GATE(channel) BIT(channel)
> +
> +#define PER(base) ((base) + 0x80)
> +#define PER_ENABLE_PWM(channel) BIT(channel)
> +
> +#define PCCR(base, pair) ((base) + 0x20 + ((pair) * 2))
> +#define PCCR_CLK_SRC(src) ((src) << 7)
> +#define PCCR_CLK_SRC_MASK GENMASK(8, 7)
> +#define PCCR_CLK_DIV_M(m) (m)
> +#define PCCR_CLK_DIV_M_MASK GENMASK(3, 0)
> +
> +#define PCR(base, channel) ((base) + 0x100 + ((channel) * 0x20))
> +#define PCR_PRESCAL_K(k) (k)
> +#define PCR_PRESCAL_K_MASK GENMASK(7, 0)
> +#define PCR_PWM_ACTIVE BIT(8)
> +
> +#define PPR(base, channel) ((base) + 0x104 + ((channel) * 0x20))
> +#define PPR_ENTIRE_CYCLE(n) ((n) << 16)
> +#define PPR_ENTIRE_CYCLE_MASK GENMASK(31, 16)
> +#define PPR_ACT_CYCLE(n) (n)
> +#define PPR_ACT_CYCLE_MASK GENMASK(15, 0)
> +
> +/* Like clrsetbits_le32 but with memory barriers */
> +void clrsetreg(void *addr, u32 clear, u32 set)
> +{
> + u32 val = readl(addr);
> +
> + val &= ~clear;
> + val |= set;
> +
> + writel(val, addr);
> +}
> +
> +void disable_pair(void *base, int pair)
> +{
> + u32 PER_clear = (PER_ENABLE_PWM(pair) | PER_ENABLE_PWM(pair + 1));
> + u32 PCGR_clear = (PCGR_CLK_GATE(pair) | PCGR_CLK_GATE(pair + 1));
> +
> + clrsetreg(PER(base), PER_clear, 0);
> + clrsetreg(PCGR(base), PCGR_clear, 0);
> +
> + log_debug("%s: pair %i, PCGR 0x%x, PER 0x%x\n",
> + __func__, pair, readl(PCGR(base)), readl(PER(base)));
> +}
> +
> +void enable_pair(void *base, int pair, int clk_src, int clk_div)
> +{
> + int div_m = fls(clk_div) - 1;
> +
> + u32 PCGR_set = (PCGR_CLK_GATE(pair) | PCGR_CLK_GATE(pair + 1));
> + u32 PCCR_clear = (PCCR_CLK_SRC_MASK | PCCR_CLK_DIV_M_MASK);
> + u32 PCCR_set = (PCCR_CLK_SRC(clk_src) | PCCR_CLK_DIV_M(div_m));
> +
> + clrsetreg(PCGR(base), 0, PCGR_set);
> + clrsetreg(PCCR(base, pair), PCCR_clear, PCCR_set);
> +
> + log_debug("%s: pair %i, clk_src %i, div_m %i, PCCR 0x%x\n",
> + __func__, pair, clk_src, div_m, readl(PCCR(base, pair)));
> +}
> +
> +void enable_channel(void *base, int channel, struct pwm_timings *timings)
> +{
> + u32 pwm_active = (timings->polarity) ? 0 : PCR_PWM_ACTIVE;
> + u32 prescale = (timings->prescale_k - 1);
> + u32 entire_cycles = timings->entire_cycles;
> + u32 active_cycles = timings->active_cycles;
> +
> + u32 PCR_clear = (PCR_PRESCAL_K_MASK | PCR_PWM_ACTIVE);
> + u32 PCR_set = (PCR_PRESCAL_K(prescale) | pwm_active);
> + u32 PPR_clear = (PPR_ENTIRE_CYCLE_MASK | PPR_ACT_CYCLE_MASK);
> + u32 PPR_set = (PPR_ENTIRE_CYCLE(entire_cycles) | PPR_ACT_CYCLE(active_cycles));
> + u32 PER_set = PER_ENABLE_PWM(channel);
> +
> + clrsetreg(PCR(base, channel), PCR_clear, PCR_set);
> + clrsetreg(PPR(base, channel), PPR_clear, PPR_set);
> + clrsetreg(PER(base), 0, PER_set);
> +
> + log_debug("%s: channel %u, clock_id %u, period_ns %u, duty_ns %u, common_div %u, prescale_k %u, entire_cycles %u, active_cycles %u, polarity %u, PCGR 0x%x, PCR 0x%x, PPR 0x%x, PER 0x%x\n",
> + __func__, channel, timings->clock_id, timings->period_ns,
> + timings->duty_ns, timings->common_div, timings->prescale_k,
> + timings->entire_cycles, timings->active_cycles,
> + timings->polarity, readl(PCGR(base)),
> + readl(PCR(base, channel)), readl(PPR(base, channel)),
> + readl(PER(base)));
> +}
> +
> +int update_channel_pair(struct sunxi_pwm_d1_priv *priv, int pair)
> +{
> + struct pwm_timings timings0 = {0};
> + struct pwm_timings timings1 = {0};
> + struct pwm_channel *channel0 = &priv->channels[pair + 0];
> + struct pwm_channel *channel1 = &priv->channels[pair + 1];
> + void *base = priv->base;
> +
> + if (channel0->updated && channel1->updated)
> + return 0;
> +
> + disable_pair(base, pair);
> +
> + if (find_pair_timings_clocked(priv->clk_srcs, channel0, channel1, &timings0, &timings1))
> + return -1;
> +
> + if (channel0->enable || channel1->enable)
> + enable_pair(base, pair, timings0.clock_id, timings0.common_div);
> +
> + if (channel0->enable)
> + enable_channel(base, pair + 0, &timings0);
> +
> + if (channel1->enable)
> + enable_channel(base, pair + 1, &timings1);
> +
> + channel0->updated = true;
> + channel1->updated = true;
> +
> + return 0;
> +}
> +
> +static int update_channels(struct udevice *dev)
> +{
> + struct sunxi_pwm_d1_priv *priv = dev_get_priv(dev);
> + int i;
> +
> + for (i = 0; i < priv->npwm; i += 2) {
> + int ret = update_channel_pair(priv, i);
> +
> + if (ret != 0)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int sunxi_pwm_d1_set_invert(struct udevice *dev, uint channel_num,
> + bool polarity)
> +{
> + struct sunxi_pwm_d1_priv *priv = dev_get_priv(dev);
> + struct pwm_channel *channel;
> +
> + if (channel_num >= priv->npwm)
> + return -EINVAL;
> +
> + channel = &priv->channels[channel_num];
> + channel->updated = (channel->polarity == polarity);
> + channel->polarity = polarity;
> +
> + return update_channels(dev);
> +}
> +
> +static int sunxi_pwm_d1_set_config(struct udevice *dev, uint channel_num,
> + uint period_ns, uint duty_ns)
> +{
> + struct sunxi_pwm_d1_priv *priv = dev_get_priv(dev);
> + struct pwm_channel *channel;
> +
> + if (channel_num >= priv->npwm)
> + return -EINVAL;
> +
> + channel = &priv->channels[channel_num];
> + channel->updated = (channel->period_ns == period_ns && channel->duty_ns == duty_ns);
> + channel->period_ns = period_ns;
> + channel->duty_ns = duty_ns;
> +
> + return update_channels(dev);
> +}
> +
> +static int sunxi_pwm_d1_set_enable(struct udevice *dev, uint channel_num, bool enable)
> +{
> + struct sunxi_pwm_d1_priv *priv = dev_get_priv(dev);
> + struct pwm_channel *channel;
> +
> + if (channel_num >= priv->npwm)
> + return -EINVAL;
> +
> + channel = &priv->channels[channel_num];
> + channel->updated = (channel->enable == enable);
> + channel->enable = enable;
> +
> + return update_channels(dev);
> +}
> +
> +static int sunxi_pwm_d1_of_to_plat(struct udevice *dev)
> +{
> + struct sunxi_pwm_d1_priv *priv = dev_get_priv(dev);
> + struct clk *clk_hosc;
> + struct clk *clk_apb0;
> + int ret;
> +
> + priv->base = dev_read_addr_ptr(dev);
> +
> + if (!priv->base) {
> + dev_err(dev, "Unset device tree offset?\n");
> + return -EINVAL;
> + }
> +
> + priv->clk_bus = devm_clk_get(dev, "bus");
> +
> + if (IS_ERR(priv->clk_bus)) {
> + dev_err(dev, "failed to get bus clock: %ld",
> + PTR_ERR(priv->clk_bus));
> + return PTR_ERR(priv->clk_bus);
> + }
> +
> + ret = clk_enable(priv->clk_bus);
> +
> + if (ret) {
> + dev_err(dev, "failed to enable bus clk: %d", ret);
> + return ret;
> + }
> +
> + clk_hosc = devm_clk_get(dev, "hosc");
> +
> + if (IS_ERR(clk_hosc)) {
> + dev_err(dev, "failed to get hosc clock: %ld",
> + PTR_ERR(clk_hosc));
> + return PTR_ERR(clk_hosc);
> + }
> +
> + clk_apb0 = devm_clk_get(dev, "apb0");
> +
> + if (IS_ERR(clk_apb0)) {
> + dev_err(dev, "failed to get apb0 clock: %ld",
> + PTR_ERR(clk_apb0));
> + return PTR_ERR(clk_apb0);
> + }
> +
> + priv->clk_srcs[0] = clk_hosc;
> + priv->clk_srcs[1] = clk_apb0;
> + priv->clk_srcs[2] = NULL;
> +
> + priv->reset = devm_reset_control_get(dev, NULL);
> +
> + if (IS_ERR(priv->reset)) {
> + dev_err(dev, "failed to get reset: %ld",
> + PTR_ERR(priv->reset));
> + return PTR_ERR(priv->reset);
> + }
> +
> + priv->npwm = 8;
> + ret = dev_read_u32(dev, "allwinner,pwm-channels", &priv->npwm);
> +
> + if (ret < 0 && ret != -EINVAL) {
> + dev_err(dev, "failed to read allwinner,pwm-channels: %d",
> + ret);
> + return ret;
> + }
> +
> + priv->channels = devm_kzalloc(dev,
> + sizeof(struct pwm_channel) * priv->npwm,
> + GFP_KERNEL);
> +
> + if (!priv->channels) {
> + dev_err(dev, "failed to read allocate pwm channels");
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int sunxi_pwm_d1_probe(struct udevice *dev)
> +{
> + struct sunxi_pwm_d1_priv *priv = dev_get_priv(dev);
> + int ret;
> +
> + ret = reset_deassert(priv->reset);
> +
> + if (ret < 0) {
> + dev_err(dev, "failed to deassert reset: %d", ret);
> + return ret;
> + }
> +
> + return update_channels(dev);
> +}
> +
> +static const struct pwm_ops sunxi_pwm_d1_ops = {
> + .set_invert = sunxi_pwm_d1_set_invert,
> + .set_config = sunxi_pwm_d1_set_config,
> + .set_enable = sunxi_pwm_d1_set_enable,
> +};
> +
> +static const struct udevice_id sunxi_pwm_d1_ids[] = {
> + { .compatible = "allwinner,sun20i-d1-pwm" },
> + { }
> +};
> +
> +U_BOOT_DRIVER(sunxi_pwm_d1) = {
> + .name = "sunxi_pwm_d1",
> + .id = UCLASS_PWM,
> + .of_match = sunxi_pwm_d1_ids,
> + .ops = &sunxi_pwm_d1_ops,
> + .of_to_plat = sunxi_pwm_d1_of_to_plat,
> + .probe = sunxi_pwm_d1_probe,
> + .priv_auto = sizeof(struct sunxi_pwm_d1_priv),
> +};
>
> --
> 2.45.1
>
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