Hello, On Mon, Nov 26, 2018 at 10:31:58PM +0100, Uwe Kleine-König wrote: > On Mon, Nov 26, 2018 at 12:23:19AM +0800, Hao Zhang wrote: > > The sun8i R40/T3/V40 PWM has 8 PWM channals and divides to 4 PWM pairs, > > each PWM pair built-in 1 clock module, 2 timer logic module and 1 > > programmable dead-time generator, it also support waveform capture. > > It has 2 clock sources OSC24M and APB1, it is different with the > > sun4i-pwm driver, Therefore add a new driver for it. > > > > Signed-off-by: Hao Zhang <hao5781...@gmail.com> > > --- > > drivers/pwm/Kconfig | 12 +- > > drivers/pwm/Makefile | 1 + > > drivers/pwm/pwm-sun8i.c | 418 > > ++++++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 430 insertions(+), 1 deletion(-) > > create mode 100644 drivers/pwm/pwm-sun8i.c > > > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > > index 504d252..6105ac8 100644 > > --- a/drivers/pwm/Kconfig > > +++ b/drivers/pwm/Kconfig > > @@ -426,7 +426,7 @@ config PWM_STMPE > > expanders. > > > > config PWM_SUN4I > > - tristate "Allwinner PWM support" > > + tristate "Allwinner SUN4I PWM support" > > depends on ARCH_SUNXI || COMPILE_TEST > > depends on HAS_IOMEM && COMMON_CLK > > help > > @@ -435,6 +435,16 @@ config PWM_SUN4I > > To compile this driver as a module, choose M here: the module > > will be called pwm-sun4i. > > > > +config PWM_SUN8I > > + tristate "Allwinner SUN8I (R40/V40/T3) PWM support" > > + depends on ARCH_SUNXI || COMPILE_TEST > > + depends on HAS_IOMEM && COMMON_CLK > > + help > > + Generic PWM framework driver for Allwinner R40/V40/T3 SoCs. > > + > > + To compile this driver as a module, choose M here: the module > > + will be called pwm-sun8i. > > + > > config PWM_TEGRA > > tristate "NVIDIA Tegra PWM support" > > depends on ARCH_TEGRA > > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > > index 9c676a0..32c8d2d 100644 > > --- a/drivers/pwm/Makefile > > +++ b/drivers/pwm/Makefile > > @@ -43,6 +43,7 @@ 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-$(CONFIG_PWM_SUN8I) += pwm-sun8i.o > > obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o > > obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o > > obj-$(CONFIG_PWM_TIEHRPWM) += pwm-tiehrpwm.o > > diff --git a/drivers/pwm/pwm-sun8i.c b/drivers/pwm/pwm-sun8i.c > > new file mode 100644 > > index 0000000..d8597e4 > > --- /dev/null > > +++ b/drivers/pwm/pwm-sun8i.c > > @@ -0,0 +1,418 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +// Copyright (C) 2018 Hao Zhang <hao5781...@gmail.com>
Given that the documentation is publically available, I suggest to add a link to it in a comment here. (http://linux-sunxi.org/File:Allwinner_R40_User_Manual_V1.0.pdf) > > + /* calculate and set prescaler, div table, PWM entire cycle */ > > + clk_div = val; > > + while (clk_div > 65535) { > > + prescaler++; > > + clk_div = val; > > + do_div(clk_div, 1U << div_id); > > + do_div(clk_div, prescaler + 1); > > + > > + if (prescaler == 255) { > > + prescaler = 0; > > + div_id++; > > + if (div_id == 9) { > > + dev_err(sun8i_pwm->chip.dev, > > + "unsupport period value\n"); > > + return -EINVAL; > > + } > > + } > > + } > > Noting the underlying formula for the calculation and the bitwidth for > the related register fields above would be good. > > > + > > + sun8i_pwm_set_value(sun8i_pwm, PWM_PERIOD_REG(ch), > > + PWM_ENTIRE_CYCLE, clk_div << 16); > > + sun8i_pwm_set_value(sun8i_pwm, PWM_CTR_REG(ch), > > + PWM_PRESCAL_K, prescaler << 0); > > + sun8i_pwm_set_value(sun8i_pwm, CLK_CFG_REG(ch), > > + CLK_DIV_M, div_id << 0); > > + > > + /* set duty cycle */ > > + val = state->period; > > + do_div(val, clk_div); > > + clk_div = state->duty_cycle; > > + do_div(clk_div, val); > > + if (clk_div > 65535) > > + clk_div = 65535; > > + > > + sun8i_pwm_set_value(sun8i_pwm, PWM_PERIOD_REG(ch), > > + PWM_ACT_CYCLE, clk_div << 0); > > Why "<< 0"? > > > + return 0; > > +} > > + > > +static int sun8i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > > + struct pwm_state *state) > > +{ > > + int ret; > > + struct sun8i_pwm_chip *sun8i_pwm = to_sun8i_pwm_chip(chip); > > + struct pwm_state cstate; > > + > > + pwm_get_state(pwm, &cstate); > > + if (!cstate.enabled) { > > + ret = clk_prepare_enable(sun8i_pwm->clk); > > + if (ret) { > > + dev_err(chip->dev, "Failed to enable PWM clock\n"); > > + return ret; > > + } > > + } > > + > > + if ((cstate.period != state->period) || > > + (cstate.duty_cycle != state->duty_cycle)) { > > + ret = sun8i_pwm_config(sun8i_pwm, pwm->hwpwm, state); > > + if (ret) { > > + dev_err(chip->dev, "Failed to config PWM\n"); > > + return ret; > > + } > > + } > > sun8i_pwm_config writes the registers that are relevant for period and > duty_cycle. When do these values take effect? If it's already here, > switching the polarity below might introduce a glitch. I think this is the case after taking a look into the reference manual. There are two 16 bit fields in the PWM_PERIOD_REG. One specifies the number of clock ticks defining the period ("PWM_ENTIRE_CYCLE") and the other the duty cycle ("PWM_ACT_CYCLE"). So if you go from duty_cycle=5 + period=10 + POLARITY_NORMAL to duty_cycle=3 + period=10 + POLARITY_INVERTED this might generate: ____ __ ______ / \____/ \_________/ \__/ ^ ^ ^ ^ Also there is a PWM_PERIOD_RDY bit field that probably has to be consulted before writing to the PWM_PERIOD_REG register. It's not entirely clear to me if the PWM_ACT_STA bit that is used for inversion is shadowed until the next period, too. That's what I assumed above. If it's not the wave might look as follows: ____ __ _____ ______ / \____/ \/ \__/ \__/ ^ ^ * ^ ^ Where * marks the point where the inversion starts to take effect. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
