| Message ID | 20240520184227.120956-3-privatesub2@gmail.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | Add support for Allwinner PWM on D1/T113s/R329 SoCs | expand |
Hi, Here's a quick review based on the experience of me writing my own driver. On Mon, May 20, 2024 at 09:42:20PM +0300, Aleksandr Shubin wrote: > + act_cycle = FIELD_GET(SUN20I_PWM_PERIOD_ACT_CYCLE, val); > + ent_cycle = FIELD_GET(SUN20I_PWM_PERIOD_ENTIRE_CYCLE, val); > + > + /* > + * The duration of the active phase should not be longer > + * than the duration of the period > + */ > + if (act_cycle > ent_cycle) > + act_cycle = ent_cycle; > + > + /* > + * We have act_cycle <= ent_cycle <= 0xffff, prescale_k <= 0x100, > + * div_m <= 8. So the multiplication fits into an u64 without > + * overflow. > + */ > + tmp = ((u64)(act_cycle) * prescale_k << div_m) * NSEC_PER_SEC; > + state->duty_cycle = DIV_ROUND_UP_ULL(tmp, clk_rate); > + tmp = ((u64)(ent_cycle) * prescale_k << div_m) * NSEC_PER_SEC; > + state->period = DIV_ROUND_UP_ULL(tmp, clk_rate); Doesn't ent_cycle require a + 1 here? Shouldn't act_cycle be > ent_cycle on 0% duty cycles? > + /* if the neighbor channel is enable, check period only */ > + use_bus_clk = FIELD_GET(SUN20I_PWM_CLK_CFG_SRC, clk_cfg) != 0; > + val = mul_u64_u64_div_u64(state->period, > + (use_bus_clk ? bus_rate : hosc_rate), > + NSEC_PER_SEC); It would be nice if it reclocked both channels. > + /* calculate prescale_k, PWM entire cycle */ > + ent_cycle = val >> div_m; > + prescale_k = DIV_ROUND_DOWN_ULL(ent_cycle, 65537); > + if (prescale_k > SUN20I_PWM_CTL_PRESCAL_K_MAX) > + prescale_k = SUN20I_PWM_CTL_PRESCAL_K_MAX; > + > + do_div(ent_cycle, prescale_k + 1); > + > + /* for N cycles, PPRx.PWM_ENTIRE_CYCLE = (N-1) */ > + reg_period = FIELD_PREP(SUN20I_PWM_PERIOD_ENTIRE_CYCLE, ent_cycle - 1); > + > + /* set duty cycle */ > + val = mul_u64_u64_div_u64(state->duty_cycle, > + (use_bus_clk ? bus_rate : hosc_rate), > + NSEC_PER_SEC); > + act_cycle = val >> div_m; > + do_div(act_cycle, prescale_k + 1); I'm not sure about this code. I don't quite get where the 65537 comes from or what's really happening here. To my understanding you either want to limit PWM_ENTIRE_CYCLE to 0xFFFE so and scale PWM_ACTIVE_CYCLE from 0 to 65535 so it can be 0x0 at 100% duty cycles and 0xFFFF at 0% duty cycles, OR you want to scale it from 0 to 65536 and check if the value is 65536, and if it is wrap it around to 0 and flip the polarity. Thanks, John.
On Mon, May 20, 2024 at 09:42:20PM +0300, Aleksandr Shubin wrote: > Allwinner's D1, T113-S3 and R329 SoCs have a quite different PWM > controllers with ones supported by pwm-sun4i driver. > > This patch adds a PWM controller driver for Allwinner's D1, > T113-S3 and R329 SoCs. The main difference between these SoCs > is the number of channels defined by the DT property. > > Co-developed-by: Brandon Cheo Fusi <fusibrandon13@gmail.com> > Signed-off-by: Brandon Cheo Fusi <fusibrandon13@gmail.com> > Signed-off-by: Aleksandr Shubin <privatesub2@gmail.com> > --- > drivers/pwm/Kconfig | 10 + > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-sun20i.c | 387 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 398 insertions(+) > create mode 100644 drivers/pwm/pwm-sun20i.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index 4b956d661755..d2e0a080eb3c 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -625,6 +625,16 @@ config PWM_SUN4I > To compile this driver as a module, choose M here: the module > will be called pwm-sun4i. > > +config PWM_SUN20I > + tristate "Allwinner D1/T113s/R329 PWM support" > + depends on ARCH_SUNXI || COMPILE_TEST > + depends on COMMON_CLK > + help > + Generic PWM framework driver for Allwinner D1/T113s/R329 SoCs. > + > + To compile this driver as a module, choose M here: the module > + will be called pwm-sun20i. > + > config PWM_SUNPLUS > tristate "Sunplus PWM support" > depends on ARCH_SUNPLUS || COMPILE_TEST > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index c5ec9e168ee7..dcad0d5a2430 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -58,6 +58,7 @@ obj-$(CONFIG_PWM_STM32) += pwm-stm32.o > obj-$(CONFIG_PWM_STM32_LP) += pwm-stm32-lp.o > obj-$(CONFIG_PWM_STMPE) += pwm-stmpe.o > obj-$(CONFIG_PWM_SUN4I) += pwm-sun4i.o > +obj-$(CONFIG_PWM_SUN20I) += pwm-sun20i.o > obj-$(CONFIG_PWM_SUNPLUS) += pwm-sunplus.o > obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o > obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o > diff --git a/drivers/pwm/pwm-sun20i.c b/drivers/pwm/pwm-sun20i.c > new file mode 100644 > index 000000000000..3e3b5b138b30 > --- /dev/null > +++ b/drivers/pwm/pwm-sun20i.c > @@ -0,0 +1,387 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * PWM Controller Driver for sunxi platforms (D1, T113-S3 and R329) > + * > + * Limitations: > + * - When the parameters change, current running period will not be completed > + * and run new settings immediately. > + * - It output HIGH-Z state when PWM channel disabled. > + * > + * Copyright (c) 2023 Aleksandr Shubin <privatesub2@gmail.com> > + */ > + > +#include <linux/bitfield.h> > +#include <linux/clk.h> > +#include <linux/err.h> > +#include <linux/io.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/pwm.h> > +#include <linux/reset.h> > + > +#define SUN20I_PWM_CLK_CFG(chan) (0x20 + (((chan) >> 1) * 0x4)) > +#define SUN20I_PWM_CLK_CFG_SRC GENMASK(8, 7) > +#define SUN20I_PWM_CLK_CFG_DIV_M GENMASK(3, 0) > +#define SUN20I_PWM_CLK_DIV_M_MAX 8 > + > +#define SUN20I_PWM_CLK_GATE 0x40 > +#define SUN20I_PWM_CLK_GATE_BYPASS(chan) BIT((chan) + 16) > +#define SUN20I_PWM_CLK_GATE_GATING(chan) BIT(chan) > + > +#define SUN20I_PWM_ENABLE 0x80 > +#define SUN20I_PWM_ENABLE_EN(chan) BIT(chan) > + > +#define SUN20I_PWM_CTL(chan) (0x100 + (chan) * 0x20) > +#define SUN20I_PWM_CTL_ACT_STA BIT(8) > +#define SUN20I_PWM_CTL_PRESCAL_K GENMASK(7, 0) > +#define SUN20I_PWM_CTL_PRESCAL_K_MAX field_max(SUN20I_PWM_CTL_PRESCAL_K) > + > +#define SUN20I_PWM_PERIOD(chan) (0x104 + (chan) * 0x20) > +#define SUN20I_PWM_PERIOD_ENTIRE_CYCLE GENMASK(31, 16) > +#define SUN20I_PWM_PERIOD_ACT_CYCLE GENMASK(15, 0) > + > +#define SUN20I_PWM_PCNTR_SIZE BIT(16) > + > +/* > + * SUN20I_PWM_MAGIC is used to quickly compute the values of the clock dividers > + * div_m (SUN20I_PWM_CLK_CFG_DIV_M) & prescale_k (SUN20I_PWM_CTL_PRESCAL_K) > + * without using a loop. These dividers limit the # of cycles in a period > + * to SUN20I_PWM_PCNTR_SIZE by applying a scaling factor of > + * 1/(div_m * (prescale_k + 1)) to the clock source. > + * > + * SUN20I_PWM_MAGIC is derived by solving for div_m and prescale_k > + * such that for a given requested period, > + * > + * i) div_m is minimized for any prescale_k ≤ SUN20I_PWM_CTL_PRESCAL_K_MAX, > + * ii) prescale_k is minimized. > + * > + * The derivation proceeds as follows, with val = # of cycles for requested > + * period: > + * > + * for a given value of div_m we want the smallest prescale_k such that > + * > + * (val >> div_m) // (prescale_k + 1) ≤ 65536 (SUN20I_PWM_PCNTR_SIZE) > + * > + * This is equivalent to: > + * > + * (val >> div_m) ≤ 65536 * (prescale_k + 1) + prescale_k > + * ⟺ (val >> div_m) ≤ 65537 * prescale_k + 65536 > + * ⟺ (val >> div_m) - 65536 ≤ 65537 * prescale_k > + * ⟺ ((val >> div_m) - 65536) / 65537 ≤ prescale_k > + * > + * As prescale_k is integer, this becomes > + * > + * ((val >> div_m) - 65536) // 65537 ≤ prescale_k > + * > + * And is minimized at > + * > + * ((val >> div_m) - 65536) // 65537 > + * > + * Now we pick the smallest div_m that satifies prescale_k ≤ 255 > + * (i.e SUN20I_PWM_CTL_PRESCAL_K_MAX), > + * > + * ((val >> div_m) - 65536) // 65537 ≤ 255 > + * ⟺ (val >> div_m) - 65536 ≤ 255 * 65537 + 65536 > + * ⟺ val >> div_m ≤ 255 * 65537 + 2 * 65536 > + * ⟺ val >> div_m < (255 * 65537 + 2 * 65536 + 1) > + * ⟺ div_m = fls((val) / (255 * 65537 + 2 * 65536 + 1)) > + * > + * Suggested by Uwe Kleine-König This is really sophisticated, that guy seems to be a genius :-) Ok, honestly: I didn't try to reunderstand this in this round. Will do that for the next iteration again. > + */ > +#define SUN20I_PWM_MAGIC (255 * 65537 + 2 * 65536 + 1) > + > +struct sun20i_pwm_chip { > + struct clk *clk_bus, *clk_hosc, *clk_apb; > + struct reset_control *rst; > + struct pwm_chip chip; > + void __iomem *base; > + /* Mutex to protect pwm apply state */ > + struct mutex mutex; > +}; Having a pwm_chip embedded in your driver private data doesn't work any more since v6.10-rc1~168^2~31. See e.g. commit 792bc12573a3 ("pwm: spear: Make use of devm_pwmchip_alloc() function") for an easy conversion to what needs to be done today. > [...] > +static int sun20i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state) > +{ > + struct sun20i_pwm_chip *sun20i_chip = to_sun20i_pwm_chip(chip); > + u64 bus_rate, hosc_rate, val, ent_cycle, act_cycle; > + u32 clk_gate, clk_cfg, pwm_en, ctl, reg_period; > + u32 prescale_k, div_m; > + bool use_bus_clk; > + int ret = 0; > + > + mutex_lock(&sun20i_chip->mutex); > + > + pwm_en = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_ENABLE); > + > + if (state->enabled != pwm->state.enabled) { > + clk_gate = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CLK_GATE); > + > + if (!state->enabled) { > + clk_gate &= ~SUN20I_PWM_CLK_GATE_GATING(pwm->hwpwm); > + pwm_en &= ~SUN20I_PWM_ENABLE_EN(pwm->hwpwm); > + sun20i_pwm_writel(sun20i_chip, pwm_en, SUN20I_PWM_ENABLE); > + sun20i_pwm_writel(sun20i_chip, clk_gate, SUN20I_PWM_CLK_GATE); return 0 here? > + } > + } > + > + if (state->polarity != pwm->state.polarity || > + state->duty_cycle != pwm->state.duty_cycle || > + state->period != pwm->state.period) { I guess this is true often enough that checking for it isn't worth the effort. Also note that with the early return suggested above, the check becomes bogous. > + ctl = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CTL(pwm->hwpwm)); > + clk_cfg = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CLK_CFG(pwm->hwpwm)); > + hosc_rate = clk_get_rate(sun20i_chip->clk_hosc); > + bus_rate = clk_get_rate(sun20i_chip->clk_apb); > + if (pwm_en & SUN20I_PWM_ENABLE_EN(pwm->hwpwm ^ 1)) { > + /* if the neighbor channel is enable, check period only */ s/enable/enabled/, maybe also mention that each SUN20I_PWM_CLK_CFG is shared by two channels. I find it irritating that SUN20I_PWM_CLK_CFG(0) == SUN20I_PWM_CLK_CFG(1). I suggest to drop the shift from the defintion and use SUN20I_PWM_CLK_CFG(pwm->hwpwm / 2) to make this more visible in the source code. > + use_bus_clk = FIELD_GET(SUN20I_PWM_CLK_CFG_SRC, clk_cfg) != 0; > + val = mul_u64_u64_div_u64(state->period, > + (use_bus_clk ? bus_rate : hosc_rate), > + NSEC_PER_SEC); > + > + div_m = FIELD_GET(SUN20I_PWM_CLK_CFG_DIV_M, clk_cfg); > + } else { > + /* check period and select clock source */ You're implicitly assuming here that bus_rate > hosc_rate. Maybe make this explicit in a comment (and check for that in .probe()?) > + use_bus_clk = false; > + val = mul_u64_u64_div_u64(state->period, hosc_rate, NSEC_PER_SEC); > + if (val <= 1) { > + use_bus_clk = true; > + val = mul_u64_u64_div_u64(state->period, bus_rate, NSEC_PER_SEC); > + if (val <= 1) { > + ret = -EINVAL; > + goto unlock_mutex; If you use a guard to lock the mutex, these gotos can just be replaced by a return statement. > + } > + } > + div_m = fls(DIV_ROUND_DOWN_ULL(val, SUN20I_PWM_MAGIC)); > + if (div_m > SUN20I_PWM_CLK_DIV_M_MAX) { > + ret = -EINVAL; > + goto unlock_mutex; > + } > + > + /* set up the CLK_DIV_M and clock CLK_SRC */ > + clk_cfg = FIELD_PREP(SUN20I_PWM_CLK_CFG_DIV_M, div_m); > + clk_cfg |= FIELD_PREP(SUN20I_PWM_CLK_CFG_SRC, use_bus_clk); > + > + sun20i_pwm_writel(sun20i_chip, clk_cfg, SUN20I_PWM_CLK_CFG(pwm->hwpwm)); > + } > + > + /* calculate prescale_k, PWM entire cycle */ > + ent_cycle = val >> div_m; > + prescale_k = DIV_ROUND_DOWN_ULL(ent_cycle, 65537); > + if (prescale_k > SUN20I_PWM_CTL_PRESCAL_K_MAX) > + prescale_k = SUN20I_PWM_CTL_PRESCAL_K_MAX; > + > + do_div(ent_cycle, prescale_k + 1); > + > + /* for N cycles, PPRx.PWM_ENTIRE_CYCLE = (N-1) */ > + reg_period = FIELD_PREP(SUN20I_PWM_PERIOD_ENTIRE_CYCLE, ent_cycle - 1); > + > + /* set duty cycle */ > + val = mul_u64_u64_div_u64(state->duty_cycle, > + (use_bus_clk ? bus_rate : hosc_rate), > + NSEC_PER_SEC); > + act_cycle = val >> div_m; > + do_div(act_cycle, prescale_k + 1); > + > + /* > + * The formula of the output period and the duty-cycle for PWM are as follows. > + * T period = (PWM01_CLK / PWM0_PRESCALE_K)^-1 * (PPR0.PWM_ENTIRE_CYCLE + 1) (PWM01_CLK / PWM0_PRESCALE_K)^-1 = PWM0_PRESCALE_K / PWM01_CLK > + * T high-level = (PWM01_CLK / PWM0_PRESCALE_K)^-1 * PPR0.PWM_ACT_CYCLE > + * Duty-cycle = T high-level / T period > + */ > + reg_period |= FIELD_PREP(SUN20I_PWM_PERIOD_ACT_CYCLE, act_cycle); > + sun20i_pwm_writel(sun20i_chip, reg_period, SUN20I_PWM_PERIOD(pwm->hwpwm)); > + > + ctl = FIELD_PREP(SUN20I_PWM_CTL_PRESCAL_K, prescale_k); > + if (state->polarity == PWM_POLARITY_NORMAL) > + ctl |= SUN20I_PWM_CTL_ACT_STA; > + > + sun20i_pwm_writel(sun20i_chip, ctl, SUN20I_PWM_CTL(pwm->hwpwm)); > + } > + > + if (state->enabled != pwm->state.enabled && state->enabled) { > + clk_gate &= ~SUN20I_PWM_CLK_GATE_BYPASS(pwm->hwpwm); > + clk_gate |= SUN20I_PWM_CLK_GATE_GATING(pwm->hwpwm); > + pwm_en |= SUN20I_PWM_ENABLE_EN(pwm->hwpwm); > + sun20i_pwm_writel(sun20i_chip, pwm_en, SUN20I_PWM_ENABLE); > + sun20i_pwm_writel(sun20i_chip, clk_gate, SUN20I_PWM_CLK_GATE); > + } > + > +unlock_mutex: > + mutex_unlock(&sun20i_chip->mutex); > + > + return ret; > +} > + > +static const struct pwm_ops sun20i_pwm_ops = { > + .apply = sun20i_pwm_apply, > + .get_state = sun20i_pwm_get_state, > +}; > + > +static const struct of_device_id sun20i_pwm_dt_ids[] = { > + { .compatible = "allwinner,sun20i-d1-pwm" }, > + { }, > +}; > +MODULE_DEVICE_TABLE(of, sun20i_pwm_dt_ids); > + > +static void sun20i_pwm_reset_ctrl_release(void *data) > +{ > + struct reset_control *rst = data; > + > + reset_control_assert(rst); > +} > + > +static int sun20i_pwm_probe(struct platform_device *pdev) > +{ > + struct sun20i_pwm_chip *sun20i_chip; > + int ret; > + > + sun20i_chip = devm_kzalloc(&pdev->dev, sizeof(*sun20i_chip), GFP_KERNEL); > + if (!sun20i_chip) > + return -ENOMEM; > + > + sun20i_chip->base = devm_platform_ioremap_resource(pdev, 0); > + if (IS_ERR(sun20i_chip->base)) > + return PTR_ERR(sun20i_chip->base); > + > + sun20i_chip->clk_bus = devm_clk_get_enabled(&pdev->dev, "bus"); > + if (IS_ERR(sun20i_chip->clk_bus)) > + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->clk_bus), > + "failed to get bus clock\n"); > + > + sun20i_chip->clk_hosc = devm_clk_get_enabled(&pdev->dev, "hosc"); > + if (IS_ERR(sun20i_chip->clk_hosc)) > + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->clk_hosc), > + "failed to get hosc clock\n"); > + > + sun20i_chip->clk_apb = devm_clk_get_enabled(&pdev->dev, "apb"); > + if (IS_ERR(sun20i_chip->clk_apb)) > + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->clk_apb), > + "failed to get apb clock\n"); > + > + sun20i_chip->rst = devm_reset_control_get_exclusive(&pdev->dev, NULL); > + if (IS_ERR(sun20i_chip->rst)) > + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->rst), > + "failed to get bus reset\n"); > + > + ret = of_property_read_u32(pdev->dev.of_node, "allwinner,pwm-channels", > + &sun20i_chip->chip.npwm); > + if (ret) > + sun20i_chip->chip.npwm = 8; > + > + if (sun20i_chip->chip.npwm > 16) { > + dev_info(&pdev->dev, "Limiting number of PWM lines from %u to 16", > + sun20i_chip->chip.npwm); > + sun20i_chip->chip.npwm = 16; > + } > + > + /* Deassert reset */ > + ret = reset_control_deassert(sun20i_chip->rst); > + if (ret) > + return dev_err_probe(&pdev->dev, ret, "failed to deassert reset\n"); > + > + ret = devm_add_action_or_reset(&pdev->dev, sun20i_pwm_reset_ctrl_release, sun20i_chip->rst); > + if (ret) > + return ret; At some point in the future this can be simplified using devm_reset_control_get_exclusive_deasserted(). See https://lore.kernel.org/linux-arm-kernel/20240621-reset-get-deasserted-v1-2-94ee76fb7b7d@pengutronix.de > + sun20i_chip->chip.dev = &pdev->dev; > + sun20i_chip->chip.ops = &sun20i_pwm_ops; > + > + mutex_init(&sun20i_chip->mutex); > + > + ret = devm_pwmchip_add(&pdev->dev, &sun20i_chip->chip); > + if (ret < 0) > + return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n"); > + > + platform_set_drvdata(pdev, sun20i_chip); This is unused. > + return 0; > +} > + > +static struct platform_driver sun20i_pwm_driver = { > + .driver = { > + .name = "sun20i-pwm", > + .of_match_table = sun20i_pwm_dt_ids, > + }, > + .probe = sun20i_pwm_probe, > +}; > +module_platform_driver(sun20i_pwm_driver); > + > +MODULE_AUTHOR("Aleksandr Shubin <privatesub2@gmail.com>"); > +MODULE_DESCRIPTION("Allwinner sun20i PWM driver"); > +MODULE_LICENSE("GPL"); Best regards Uwe
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 4b956d661755..d2e0a080eb3c 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -625,6 +625,16 @@ config PWM_SUN4I To compile this driver as a module, choose M here: the module will be called pwm-sun4i. +config PWM_SUN20I + tristate "Allwinner D1/T113s/R329 PWM support" + depends on ARCH_SUNXI || COMPILE_TEST + depends on COMMON_CLK + help + Generic PWM framework driver for Allwinner D1/T113s/R329 SoCs. + + To compile this driver as a module, choose M here: the module + will be called pwm-sun20i. + config PWM_SUNPLUS tristate "Sunplus PWM support" depends on ARCH_SUNPLUS || COMPILE_TEST diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index c5ec9e168ee7..dcad0d5a2430 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -58,6 +58,7 @@ obj-$(CONFIG_PWM_STM32) += pwm-stm32.o obj-$(CONFIG_PWM_STM32_LP) += pwm-stm32-lp.o obj-$(CONFIG_PWM_STMPE) += pwm-stmpe.o obj-$(CONFIG_PWM_SUN4I) += pwm-sun4i.o +obj-$(CONFIG_PWM_SUN20I) += pwm-sun20i.o obj-$(CONFIG_PWM_SUNPLUS) += pwm-sunplus.o obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o diff --git a/drivers/pwm/pwm-sun20i.c b/drivers/pwm/pwm-sun20i.c new file mode 100644 index 000000000000..3e3b5b138b30 --- /dev/null +++ b/drivers/pwm/pwm-sun20i.c @@ -0,0 +1,387 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * PWM Controller Driver for sunxi platforms (D1, T113-S3 and R329) + * + * Limitations: + * - When the parameters change, current running period will not be completed + * and run new settings immediately. + * - It output HIGH-Z state when PWM channel disabled. + * + * Copyright (c) 2023 Aleksandr Shubin <privatesub2@gmail.com> + */ + +#include <linux/bitfield.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/reset.h> + +#define SUN20I_PWM_CLK_CFG(chan) (0x20 + (((chan) >> 1) * 0x4)) +#define SUN20I_PWM_CLK_CFG_SRC GENMASK(8, 7) +#define SUN20I_PWM_CLK_CFG_DIV_M GENMASK(3, 0) +#define SUN20I_PWM_CLK_DIV_M_MAX 8 + +#define SUN20I_PWM_CLK_GATE 0x40 +#define SUN20I_PWM_CLK_GATE_BYPASS(chan) BIT((chan) + 16) +#define SUN20I_PWM_CLK_GATE_GATING(chan) BIT(chan) + +#define SUN20I_PWM_ENABLE 0x80 +#define SUN20I_PWM_ENABLE_EN(chan) BIT(chan) + +#define SUN20I_PWM_CTL(chan) (0x100 + (chan) * 0x20) +#define SUN20I_PWM_CTL_ACT_STA BIT(8) +#define SUN20I_PWM_CTL_PRESCAL_K GENMASK(7, 0) +#define SUN20I_PWM_CTL_PRESCAL_K_MAX field_max(SUN20I_PWM_CTL_PRESCAL_K) + +#define SUN20I_PWM_PERIOD(chan) (0x104 + (chan) * 0x20) +#define SUN20I_PWM_PERIOD_ENTIRE_CYCLE GENMASK(31, 16) +#define SUN20I_PWM_PERIOD_ACT_CYCLE GENMASK(15, 0) + +#define SUN20I_PWM_PCNTR_SIZE BIT(16) + +/* + * SUN20I_PWM_MAGIC is used to quickly compute the values of the clock dividers + * div_m (SUN20I_PWM_CLK_CFG_DIV_M) & prescale_k (SUN20I_PWM_CTL_PRESCAL_K) + * without using a loop. These dividers limit the # of cycles in a period + * to SUN20I_PWM_PCNTR_SIZE by applying a scaling factor of + * 1/(div_m * (prescale_k + 1)) to the clock source. + * + * SUN20I_PWM_MAGIC is derived by solving for div_m and prescale_k + * such that for a given requested period, + * + * i) div_m is minimized for any prescale_k ≤ SUN20I_PWM_CTL_PRESCAL_K_MAX, + * ii) prescale_k is minimized. + * + * The derivation proceeds as follows, with val = # of cycles for requested + * period: + * + * for a given value of div_m we want the smallest prescale_k such that + * + * (val >> div_m) // (prescale_k + 1) ≤ 65536 (SUN20I_PWM_PCNTR_SIZE) + * + * This is equivalent to: + * + * (val >> div_m) ≤ 65536 * (prescale_k + 1) + prescale_k + * ⟺ (val >> div_m) ≤ 65537 * prescale_k + 65536 + * ⟺ (val >> div_m) - 65536 ≤ 65537 * prescale_k + * ⟺ ((val >> div_m) - 65536) / 65537 ≤ prescale_k + * + * As prescale_k is integer, this becomes + * + * ((val >> div_m) - 65536) // 65537 ≤ prescale_k + * + * And is minimized at + * + * ((val >> div_m) - 65536) // 65537 + * + * Now we pick the smallest div_m that satifies prescale_k ≤ 255 + * (i.e SUN20I_PWM_CTL_PRESCAL_K_MAX), + * + * ((val >> div_m) - 65536) // 65537 ≤ 255 + * ⟺ (val >> div_m) - 65536 ≤ 255 * 65537 + 65536 + * ⟺ val >> div_m ≤ 255 * 65537 + 2 * 65536 + * ⟺ val >> div_m < (255 * 65537 + 2 * 65536 + 1) + * ⟺ div_m = fls((val) / (255 * 65537 + 2 * 65536 + 1)) + * + * Suggested by Uwe Kleine-König + */ +#define SUN20I_PWM_MAGIC (255 * 65537 + 2 * 65536 + 1) + +struct sun20i_pwm_chip { + struct clk *clk_bus, *clk_hosc, *clk_apb; + struct reset_control *rst; + struct pwm_chip chip; + void __iomem *base; + /* Mutex to protect pwm apply state */ + struct mutex mutex; +}; + +static inline struct sun20i_pwm_chip *to_sun20i_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct sun20i_pwm_chip, chip); +} + +static inline u32 sun20i_pwm_readl(struct sun20i_pwm_chip *chip, + unsigned long offset) +{ + return readl(chip->base + offset); +} + +static inline void sun20i_pwm_writel(struct sun20i_pwm_chip *chip, + u32 val, unsigned long offset) +{ + writel(val, chip->base + offset); +} + +static int sun20i_pwm_get_state(struct pwm_chip *chip, + struct pwm_device *pwm, + struct pwm_state *state) +{ + struct sun20i_pwm_chip *sun20i_chip = to_sun20i_pwm_chip(chip); + u16 ent_cycle, act_cycle, prescale_k; + u64 clk_rate, tmp; + u8 div_m; + u32 val; + + mutex_lock(&sun20i_chip->mutex); + + val = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CLK_CFG(pwm->hwpwm)); + div_m = FIELD_GET(SUN20I_PWM_CLK_CFG_DIV_M, val); + if (div_m > SUN20I_PWM_CLK_DIV_M_MAX) + div_m = SUN20I_PWM_CLK_DIV_M_MAX; + + if (FIELD_GET(SUN20I_PWM_CLK_CFG_SRC, val) == 0) + clk_rate = clk_get_rate(sun20i_chip->clk_hosc); + else + clk_rate = clk_get_rate(sun20i_chip->clk_apb); + + val = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CTL(pwm->hwpwm)); + state->polarity = (SUN20I_PWM_CTL_ACT_STA & val) ? + PWM_POLARITY_NORMAL : PWM_POLARITY_INVERSED; + + prescale_k = FIELD_GET(SUN20I_PWM_CTL_PRESCAL_K, val) + 1; + + val = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_ENABLE); + state->enabled = (SUN20I_PWM_ENABLE_EN(pwm->hwpwm) & val) ? true : false; + + val = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_PERIOD(pwm->hwpwm)); + + mutex_unlock(&sun20i_chip->mutex); + + act_cycle = FIELD_GET(SUN20I_PWM_PERIOD_ACT_CYCLE, val); + ent_cycle = FIELD_GET(SUN20I_PWM_PERIOD_ENTIRE_CYCLE, val); + + /* + * The duration of the active phase should not be longer + * than the duration of the period + */ + if (act_cycle > ent_cycle) + act_cycle = ent_cycle; + + /* + * We have act_cycle <= ent_cycle <= 0xffff, prescale_k <= 0x100, + * div_m <= 8. So the multiplication fits into an u64 without + * overflow. + */ + tmp = ((u64)(act_cycle) * prescale_k << div_m) * NSEC_PER_SEC; + state->duty_cycle = DIV_ROUND_UP_ULL(tmp, clk_rate); + tmp = ((u64)(ent_cycle) * prescale_k << div_m) * NSEC_PER_SEC; + state->period = DIV_ROUND_UP_ULL(tmp, clk_rate); + + return 0; +} + +static int sun20i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct sun20i_pwm_chip *sun20i_chip = to_sun20i_pwm_chip(chip); + u64 bus_rate, hosc_rate, val, ent_cycle, act_cycle; + u32 clk_gate, clk_cfg, pwm_en, ctl, reg_period; + u32 prescale_k, div_m; + bool use_bus_clk; + int ret = 0; + + mutex_lock(&sun20i_chip->mutex); + + pwm_en = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_ENABLE); + + if (state->enabled != pwm->state.enabled) { + clk_gate = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CLK_GATE); + + if (!state->enabled) { + clk_gate &= ~SUN20I_PWM_CLK_GATE_GATING(pwm->hwpwm); + pwm_en &= ~SUN20I_PWM_ENABLE_EN(pwm->hwpwm); + sun20i_pwm_writel(sun20i_chip, pwm_en, SUN20I_PWM_ENABLE); + sun20i_pwm_writel(sun20i_chip, clk_gate, SUN20I_PWM_CLK_GATE); + } + } + + if (state->polarity != pwm->state.polarity || + state->duty_cycle != pwm->state.duty_cycle || + state->period != pwm->state.period) { + ctl = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CTL(pwm->hwpwm)); + clk_cfg = sun20i_pwm_readl(sun20i_chip, SUN20I_PWM_CLK_CFG(pwm->hwpwm)); + hosc_rate = clk_get_rate(sun20i_chip->clk_hosc); + bus_rate = clk_get_rate(sun20i_chip->clk_apb); + if (pwm_en & SUN20I_PWM_ENABLE_EN(pwm->hwpwm ^ 1)) { + /* if the neighbor channel is enable, check period only */ + use_bus_clk = FIELD_GET(SUN20I_PWM_CLK_CFG_SRC, clk_cfg) != 0; + val = mul_u64_u64_div_u64(state->period, + (use_bus_clk ? bus_rate : hosc_rate), + NSEC_PER_SEC); + + div_m = FIELD_GET(SUN20I_PWM_CLK_CFG_DIV_M, clk_cfg); + } else { + /* check period and select clock source */ + use_bus_clk = false; + val = mul_u64_u64_div_u64(state->period, hosc_rate, NSEC_PER_SEC); + if (val <= 1) { + use_bus_clk = true; + val = mul_u64_u64_div_u64(state->period, bus_rate, NSEC_PER_SEC); + if (val <= 1) { + ret = -EINVAL; + goto unlock_mutex; + } + } + div_m = fls(DIV_ROUND_DOWN_ULL(val, SUN20I_PWM_MAGIC)); + if (div_m > SUN20I_PWM_CLK_DIV_M_MAX) { + ret = -EINVAL; + goto unlock_mutex; + } + + /* set up the CLK_DIV_M and clock CLK_SRC */ + clk_cfg = FIELD_PREP(SUN20I_PWM_CLK_CFG_DIV_M, div_m); + clk_cfg |= FIELD_PREP(SUN20I_PWM_CLK_CFG_SRC, use_bus_clk); + + sun20i_pwm_writel(sun20i_chip, clk_cfg, SUN20I_PWM_CLK_CFG(pwm->hwpwm)); + } + + /* calculate prescale_k, PWM entire cycle */ + ent_cycle = val >> div_m; + prescale_k = DIV_ROUND_DOWN_ULL(ent_cycle, 65537); + if (prescale_k > SUN20I_PWM_CTL_PRESCAL_K_MAX) + prescale_k = SUN20I_PWM_CTL_PRESCAL_K_MAX; + + do_div(ent_cycle, prescale_k + 1); + + /* for N cycles, PPRx.PWM_ENTIRE_CYCLE = (N-1) */ + reg_period = FIELD_PREP(SUN20I_PWM_PERIOD_ENTIRE_CYCLE, ent_cycle - 1); + + /* set duty cycle */ + val = mul_u64_u64_div_u64(state->duty_cycle, + (use_bus_clk ? bus_rate : hosc_rate), + NSEC_PER_SEC); + act_cycle = val >> div_m; + do_div(act_cycle, prescale_k + 1); + + /* + * The formula of the output period and the duty-cycle for PWM are as follows. + * T period = (PWM01_CLK / PWM0_PRESCALE_K)^-1 * (PPR0.PWM_ENTIRE_CYCLE + 1) + * T high-level = (PWM01_CLK / PWM0_PRESCALE_K)^-1 * PPR0.PWM_ACT_CYCLE + * Duty-cycle = T high-level / T period + */ + reg_period |= FIELD_PREP(SUN20I_PWM_PERIOD_ACT_CYCLE, act_cycle); + sun20i_pwm_writel(sun20i_chip, reg_period, SUN20I_PWM_PERIOD(pwm->hwpwm)); + + ctl = FIELD_PREP(SUN20I_PWM_CTL_PRESCAL_K, prescale_k); + if (state->polarity == PWM_POLARITY_NORMAL) + ctl |= SUN20I_PWM_CTL_ACT_STA; + + sun20i_pwm_writel(sun20i_chip, ctl, SUN20I_PWM_CTL(pwm->hwpwm)); + } + + if (state->enabled != pwm->state.enabled && state->enabled) { + clk_gate &= ~SUN20I_PWM_CLK_GATE_BYPASS(pwm->hwpwm); + clk_gate |= SUN20I_PWM_CLK_GATE_GATING(pwm->hwpwm); + pwm_en |= SUN20I_PWM_ENABLE_EN(pwm->hwpwm); + sun20i_pwm_writel(sun20i_chip, pwm_en, SUN20I_PWM_ENABLE); + sun20i_pwm_writel(sun20i_chip, clk_gate, SUN20I_PWM_CLK_GATE); + } + +unlock_mutex: + mutex_unlock(&sun20i_chip->mutex); + + return ret; +} + +static const struct pwm_ops sun20i_pwm_ops = { + .apply = sun20i_pwm_apply, + .get_state = sun20i_pwm_get_state, +}; + +static const struct of_device_id sun20i_pwm_dt_ids[] = { + { .compatible = "allwinner,sun20i-d1-pwm" }, + { }, +}; +MODULE_DEVICE_TABLE(of, sun20i_pwm_dt_ids); + +static void sun20i_pwm_reset_ctrl_release(void *data) +{ + struct reset_control *rst = data; + + reset_control_assert(rst); +} + +static int sun20i_pwm_probe(struct platform_device *pdev) +{ + struct sun20i_pwm_chip *sun20i_chip; + int ret; + + sun20i_chip = devm_kzalloc(&pdev->dev, sizeof(*sun20i_chip), GFP_KERNEL); + if (!sun20i_chip) + return -ENOMEM; + + sun20i_chip->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(sun20i_chip->base)) + return PTR_ERR(sun20i_chip->base); + + sun20i_chip->clk_bus = devm_clk_get_enabled(&pdev->dev, "bus"); + if (IS_ERR(sun20i_chip->clk_bus)) + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->clk_bus), + "failed to get bus clock\n"); + + sun20i_chip->clk_hosc = devm_clk_get_enabled(&pdev->dev, "hosc"); + if (IS_ERR(sun20i_chip->clk_hosc)) + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->clk_hosc), + "failed to get hosc clock\n"); + + sun20i_chip->clk_apb = devm_clk_get_enabled(&pdev->dev, "apb"); + if (IS_ERR(sun20i_chip->clk_apb)) + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->clk_apb), + "failed to get apb clock\n"); + + sun20i_chip->rst = devm_reset_control_get_exclusive(&pdev->dev, NULL); + if (IS_ERR(sun20i_chip->rst)) + return dev_err_probe(&pdev->dev, PTR_ERR(sun20i_chip->rst), + "failed to get bus reset\n"); + + ret = of_property_read_u32(pdev->dev.of_node, "allwinner,pwm-channels", + &sun20i_chip->chip.npwm); + if (ret) + sun20i_chip->chip.npwm = 8; + + if (sun20i_chip->chip.npwm > 16) { + dev_info(&pdev->dev, "Limiting number of PWM lines from %u to 16", + sun20i_chip->chip.npwm); + sun20i_chip->chip.npwm = 16; + } + + /* Deassert reset */ + ret = reset_control_deassert(sun20i_chip->rst); + if (ret) + return dev_err_probe(&pdev->dev, ret, "failed to deassert reset\n"); + + ret = devm_add_action_or_reset(&pdev->dev, sun20i_pwm_reset_ctrl_release, sun20i_chip->rst); + if (ret) + return ret; + + sun20i_chip->chip.dev = &pdev->dev; + sun20i_chip->chip.ops = &sun20i_pwm_ops; + + mutex_init(&sun20i_chip->mutex); + + ret = devm_pwmchip_add(&pdev->dev, &sun20i_chip->chip); + if (ret < 0) + return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n"); + + platform_set_drvdata(pdev, sun20i_chip); + + return 0; +} + +static struct platform_driver sun20i_pwm_driver = { + .driver = { + .name = "sun20i-pwm", + .of_match_table = sun20i_pwm_dt_ids, + }, + .probe = sun20i_pwm_probe, +}; +module_platform_driver(sun20i_pwm_driver); + +MODULE_AUTHOR("Aleksandr Shubin <privatesub2@gmail.com>"); +MODULE_DESCRIPTION("Allwinner sun20i PWM driver"); +MODULE_LICENSE("GPL");