| Message ID | 20221121174228.93670-3-fnkl.kernel@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PWM and keyboard backlight driver for ARM Macs | expand |
On Mon, Nov 21, 2022 at 08:42:26PM +0300, Sasha Finkelstein wrote: > Adds the Apple PWM controller driver. > > Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com> > Acked-by: Sven Peter <sven@svenpeter.dev> > --- > drivers/pwm/Kconfig | 12 ++++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-apple.c | 127 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 140 insertions(+) > create mode 100644 drivers/pwm/pwm-apple.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index 60d13a949bc5..c3be11468414 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -51,6 +51,18 @@ config PWM_AB8500 > To compile this driver as a module, choose M here: the module > will be called pwm-ab8500. > > +config PWM_APPLE > + tristate "Apple SoC PWM support" > + depends on ARCH_APPLE || COMPILE_TEST > + help > + Generic PWM framework driver for PWM controller present on > + Apple SoCs > + > + Say Y here if you have an ARM Apple laptop, otherwise say N > + > + To compile this driver as a module, choose M here: the module > + will be called pwm-apple. > + > config PWM_ATMEL > tristate "Atmel PWM support" > depends on ARCH_AT91 || COMPILE_TEST > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index 7bf1a29f02b8..19899b912e00 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -2,6 +2,7 @@ > obj-$(CONFIG_PWM) += core.o > obj-$(CONFIG_PWM_SYSFS) += sysfs.o > obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o > +obj-$(CONFIG_PWM_APPLE) += pwm-apple.o > obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o > obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o > obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o > diff --git a/drivers/pwm/pwm-apple.c b/drivers/pwm/pwm-apple.c > new file mode 100644 > index 000000000000..b0c3f86fd578 > --- /dev/null > +++ b/drivers/pwm/pwm-apple.c > @@ -0,0 +1,127 @@ > +// SPDX-License-Identifier: GPL-2.0 OR MIT Kernel code is generally GPL-2.0 only. No other PWM driver is MIT licensed. So why this one. Mixing licenses is a problem because few people look at the licenses when copying code around. > +/* > + * Driver for the Apple SoC PWM controller > + * > + * Copyright The Asahi Linux Contributors > + */ > + > +#include <linux/clk.h> > +#include <linux/io.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/pm_runtime.h> > +#include <linux/pwm.h> > + > +#define PWM_CONTROL 0x00 > +#define PWM_ON_CYCLES 0x1c > +#define PWM_OFF_CYCLES 0x18 > + > +#define CTRL_ENABLE BIT(0) > +#define CTRL_MODE BIT(2) > +#define CTRL_UPDATE BIT(5) > +#define CTRL_TRIGGER BIT(9) > +#define CTRL_INVERT BIT(10) > +#define CTRL_OUTPUT_ENABLE BIT(14) > + > +struct apple_pwm { > + struct pwm_chip chip; > + void __iomem *base; > + u64 clkrate; > +}; > + > +static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state) > +{ > + struct apple_pwm *fpwm; > + u64 on_cycles, off_cycles; > + > + fpwm = container_of(chip, struct apple_pwm, chip); > + if (state->enabled) { > + on_cycles = mul_u64_u64_div_u64(fpwm->clkrate, > + state->duty_cycle, NSEC_PER_SEC); > + off_cycles = mul_u64_u64_div_u64(fpwm->clkrate, > + state->period, NSEC_PER_SEC) - on_cycles; > + writel(on_cycles, fpwm->base + PWM_ON_CYCLES); > + writel(off_cycles, fpwm->base + PWM_OFF_CYCLES); > + writel(CTRL_ENABLE | CTRL_OUTPUT_ENABLE | CTRL_UPDATE, > + fpwm->base + PWM_CONTROL); > + } else { > + writel(0, fpwm->base + PWM_CONTROL); > + } > + return 0; > +} > + > +static void apple_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > + struct pwm_state *state) > +{ > + struct apple_pwm *fpwm; > + u32 on_cycles, off_cycles, ctrl; > + > + fpwm = container_of(chip, struct apple_pwm, chip); > + > + ctrl = readl(fpwm->base + PWM_CONTROL); > + on_cycles = readl(fpwm->base + PWM_ON_CYCLES); > + off_cycles = readl(fpwm->base + PWM_OFF_CYCLES); > + > + state->enabled = (ctrl & CTRL_ENABLE) && (ctrl & CTRL_OUTPUT_ENABLE); > + state->polarity = PWM_POLARITY_NORMAL; > + state->duty_cycle = div_u64(on_cycles, fpwm->clkrate) * NSEC_PER_SEC; > + state->period = div_u64(off_cycles + on_cycles, fpwm->clkrate) * NSEC_PER_SEC; > +} > + > +static const struct pwm_ops apple_pwm_ops = { > + .apply = apple_pwm_apply, > + .get_state = apple_pwm_get_state, > + .owner = THIS_MODULE, > +}; > + > +static int apple_pwm_probe(struct platform_device *pdev) > +{ > + struct apple_pwm *pwm; > + struct clk *clk; > + int ret; > + > + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); > + if (!pwm) > + return -ENOMEM; > + > + pwm->base = devm_platform_ioremap_resource(pdev, 0); > + if (IS_ERR(pwm->base)) > + return PTR_ERR(pwm->base); > + > + platform_set_drvdata(pdev, pwm); > + > + clk = devm_clk_get_enabled(&pdev->dev, NULL); > + if (IS_ERR(clk)) > + return PTR_ERR(clk); > + > + pwm->clkrate = clk_get_rate(clk); > + pwm->chip.dev = &pdev->dev; > + pwm->chip.npwm = 1; > + pwm->chip.ops = &apple_pwm_ops; > + > + ret = devm_pwmchip_add(&pdev->dev, &pwm->chip); This symbol is EXPORT_SYMBOL_GPL. So how can this module be MIT licensed? > + return ret; > +} > + > +static const struct of_device_id apple_pwm_of_match[] = { > + { .compatible = "apple,s5l-fpwm" }, > + {} > +}; > +MODULE_DEVICE_TABLE(of, apple_pwm_of_match); > + > +static struct platform_driver apple_pwm_driver = { > + .probe = apple_pwm_probe, > + .driver = { > + .name = "apple-pwm", > + .owner = THIS_MODULE, This line should be dropped. > + .of_match_table = apple_pwm_of_match, > + }, > +}; > +module_platform_driver(apple_pwm_driver); > + > +MODULE_DESCRIPTION("Apple SoC PWM driver"); > +MODULE_LICENSE("Dual MIT/GPL"); > -- > 2.38.1 > >
On 23/11/2022 11.24, Rob Herring wrote: > On Mon, Nov 21, 2022 at 08:42:26PM +0300, Sasha Finkelstein wrote: >> diff --git a/drivers/pwm/pwm-apple.c b/drivers/pwm/pwm-apple.c >> new file mode 100644 >> index 000000000000..b0c3f86fd578 >> --- /dev/null >> +++ b/drivers/pwm/pwm-apple.c >> @@ -0,0 +1,127 @@ >> +// SPDX-License-Identifier: GPL-2.0 OR MIT > > Kernel code is generally GPL-2.0 only. No other PWM driver is MIT > licensed. So why this one. > > Mixing licenses is a problem because few people look at the licenses > when copying code around. *Sigh*. We encourage the use of MIT dual-licensing as a project to allow other OSes to port the drivers over without having to rewrite them, for any driver written from scratch. We've had this conversation quite a few times already... >> + >> + ret = devm_pwmchip_add(&pdev->dev, &pwm->chip); > > This symbol is EXPORT_SYMBOL_GPL. So how can this module be MIT > licensed? Because they are compatible licenses. The combination of this driver and the kernel is GPL, but this driver itself is MIT. People are free to port it to other OSes and reimplement devm_pwmchip_add or replace the call with something else. The EXPORT_SYMBOL_GPL stuff is about blocking *proprietary* GPL-incompatible modules from using those symbols. This is a GPL-compatible, explicitly dual-licensed module. In this case the driver is trivial enough there isn't much to gain from dual-licensing since the parts that matter (the reverse engineering) are not copyrightable, but I still find it silly that we keep getting told more permissive licensing is a problem. People are free to dual-license their work as they see fit, it's a fundamental freedom in free software, and plenty of kernel code is dual-licensed like this (including much of DRM and entire GPU drivers). - Hector
Hello, On Mon, Nov 21, 2022 at 08:42:26PM +0300, Sasha Finkelstein wrote: > Adds the Apple PWM controller driver. > > Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com> > Acked-by: Sven Peter <sven@svenpeter.dev> > --- > drivers/pwm/Kconfig | 12 ++++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-apple.c | 127 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 140 insertions(+) > create mode 100644 drivers/pwm/pwm-apple.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index 60d13a949bc5..c3be11468414 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -51,6 +51,18 @@ config PWM_AB8500 > To compile this driver as a module, choose M here: the module > will be called pwm-ab8500. > > +config PWM_APPLE > + tristate "Apple SoC PWM support" > + depends on ARCH_APPLE || COMPILE_TEST > + help > + Generic PWM framework driver for PWM controller present on > + Apple SoCs > + > + Say Y here if you have an ARM Apple laptop, otherwise say N > + > + To compile this driver as a module, choose M here: the module > + will be called pwm-apple. > + > config PWM_ATMEL > tristate "Atmel PWM support" > depends on ARCH_AT91 || COMPILE_TEST > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index 7bf1a29f02b8..19899b912e00 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -2,6 +2,7 @@ > obj-$(CONFIG_PWM) += core.o > obj-$(CONFIG_PWM_SYSFS) += sysfs.o > obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o > +obj-$(CONFIG_PWM_APPLE) += pwm-apple.o > obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o > obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o > obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o > diff --git a/drivers/pwm/pwm-apple.c b/drivers/pwm/pwm-apple.c > new file mode 100644 > index 000000000000..b0c3f86fd578 > --- /dev/null > +++ b/drivers/pwm/pwm-apple.c > @@ -0,0 +1,127 @@ > +// SPDX-License-Identifier: GPL-2.0 OR MIT > +/* > + * Driver for the Apple SoC PWM controller > + * > + * Copyright The Asahi Linux Contributors > + */ > + > +#include <linux/clk.h> > +#include <linux/io.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/pm_runtime.h> > +#include <linux/pwm.h> > + > +#define PWM_CONTROL 0x00 > +#define PWM_ON_CYCLES 0x1c > +#define PWM_OFF_CYCLES 0x18 > + > +#define CTRL_ENABLE BIT(0) > +#define CTRL_MODE BIT(2) > +#define CTRL_UPDATE BIT(5) > +#define CTRL_TRIGGER BIT(9) > +#define CTRL_INVERT BIT(10) > +#define CTRL_OUTPUT_ENABLE BIT(14) Please use a driver specific prefix on these defines to make it obvious that they are driver specific. > +struct apple_pwm { > + struct pwm_chip chip; > + void __iomem *base; > + u64 clkrate; > +}; > + > +static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state) > +{ > + struct apple_pwm *fpwm; > + u64 on_cycles, off_cycles; > + > + fpwm = container_of(chip, struct apple_pwm, chip); Please introduce a macro or static inline for that. > + if (state->enabled) { > + on_cycles = mul_u64_u64_div_u64(fpwm->clkrate, > + state->duty_cycle, NSEC_PER_SEC); This might overflow for big values of clkrate and duty_cycle. The usual approach is to check for clkrate <= NSEC_PER_SEC. See pwm-lpc18xx-sct.c for an example. > + off_cycles = mul_u64_u64_div_u64(fpwm->clkrate, > + state->period, NSEC_PER_SEC) - on_cycles; > + writel(on_cycles, fpwm->base + PWM_ON_CYCLES); You're assuming on_cycles to fit into an u32 here. Please ensure that's a valid claim. > + writel(off_cycles, fpwm->base + PWM_OFF_CYCLES); > + writel(CTRL_ENABLE | CTRL_OUTPUT_ENABLE | CTRL_UPDATE, > + fpwm->base + PWM_CONTROL); How does the hardware behave on updates? Are the register values shadowed until PWM_CONTROL is written? Or until the next period starts? Please document this at the top of the driver file, in the same format as e.g. pwm-sl28cpld.c does. (The relevant section is called "Limitations", actually "Hardware properties" would be a better name, but please stick to the former for easier greppability.) > + } else { > + writel(0, fpwm->base + PWM_CONTROL); > + } > + return 0; > +} > + > +static void apple_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > + struct pwm_state *state) > +{ > + struct apple_pwm *fpwm; > + u32 on_cycles, off_cycles, ctrl; > + > + fpwm = container_of(chip, struct apple_pwm, chip); > + > + ctrl = readl(fpwm->base + PWM_CONTROL); > + on_cycles = readl(fpwm->base + PWM_ON_CYCLES); > + off_cycles = readl(fpwm->base + PWM_OFF_CYCLES); > + > + state->enabled = (ctrl & CTRL_ENABLE) && (ctrl & CTRL_OUTPUT_ENABLE); > + state->polarity = PWM_POLARITY_NORMAL; > + state->duty_cycle = div_u64(on_cycles, fpwm->clkrate) * NSEC_PER_SEC; > + state->period = div_u64(off_cycles + on_cycles, fpwm->clkrate) * NSEC_PER_SEC; You're loosing precision here, always do the division last. Also the rounding is wrong. Enabling PWM_DEBUG + some non-trivial testing should tell you that. > +} > + > +static const struct pwm_ops apple_pwm_ops = { > + .apply = apple_pwm_apply, > + .get_state = apple_pwm_get_state, > + .owner = THIS_MODULE, > +}; > + > +static int apple_pwm_probe(struct platform_device *pdev) > +{ > + struct apple_pwm *pwm; The name "pwm" is usually (only) used for struct pwm_device variables. Please pick another name (something like ddata or pc are usual names), above you picked "fpwm", which I could live with, too. > + struct clk *clk; > + int ret; > + > + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); > + if (!pwm) > + return -ENOMEM; > + > + pwm->base = devm_platform_ioremap_resource(pdev, 0); > + if (IS_ERR(pwm->base)) > + return PTR_ERR(pwm->base); > + > + platform_set_drvdata(pdev, pwm); This is unused. > + clk = devm_clk_get_enabled(&pdev->dev, NULL); > + if (IS_ERR(clk)) Error message please, preferably using dev_err_probe. > + return PTR_ERR(clk); > + > + pwm->clkrate = clk_get_rate(clk); > + pwm->chip.dev = &pdev->dev; > + pwm->chip.npwm = 1; > + pwm->chip.ops = &apple_pwm_ops; > + > + ret = devm_pwmchip_add(&pdev->dev, &pwm->chip); Ditto. > + return ret; > +} > + > +static const struct of_device_id apple_pwm_of_match[] = { > + { .compatible = "apple,s5l-fpwm" }, > + {} > +}; > +MODULE_DEVICE_TABLE(of, apple_pwm_of_match); > + > +static struct platform_driver apple_pwm_driver = { > + .probe = apple_pwm_probe, > + .driver = { > + .name = "apple-pwm", > + .owner = THIS_MODULE, > + .of_match_table = apple_pwm_of_match, > + }, > +}; > +module_platform_driver(apple_pwm_driver); > + > +MODULE_DESCRIPTION("Apple SoC PWM driver"); > +MODULE_LICENSE("Dual MIT/GPL");
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 60d13a949bc5..c3be11468414 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -51,6 +51,18 @@ config PWM_AB8500 To compile this driver as a module, choose M here: the module will be called pwm-ab8500. +config PWM_APPLE + tristate "Apple SoC PWM support" + depends on ARCH_APPLE || COMPILE_TEST + help + Generic PWM framework driver for PWM controller present on + Apple SoCs + + Say Y here if you have an ARM Apple laptop, otherwise say N + + To compile this driver as a module, choose M here: the module + will be called pwm-apple. + config PWM_ATMEL tristate "Atmel PWM support" depends on ARCH_AT91 || COMPILE_TEST diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index 7bf1a29f02b8..19899b912e00 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -2,6 +2,7 @@ obj-$(CONFIG_PWM) += core.o obj-$(CONFIG_PWM_SYSFS) += sysfs.o obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o +obj-$(CONFIG_PWM_APPLE) += pwm-apple.o obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o diff --git a/drivers/pwm/pwm-apple.c b/drivers/pwm/pwm-apple.c new file mode 100644 index 000000000000..b0c3f86fd578 --- /dev/null +++ b/drivers/pwm/pwm-apple.c @@ -0,0 +1,127 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT +/* + * Driver for the Apple SoC PWM controller + * + * Copyright The Asahi Linux Contributors + */ + +#include <linux/clk.h> +#include <linux/io.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/pm_runtime.h> +#include <linux/pwm.h> + +#define PWM_CONTROL 0x00 +#define PWM_ON_CYCLES 0x1c +#define PWM_OFF_CYCLES 0x18 + +#define CTRL_ENABLE BIT(0) +#define CTRL_MODE BIT(2) +#define CTRL_UPDATE BIT(5) +#define CTRL_TRIGGER BIT(9) +#define CTRL_INVERT BIT(10) +#define CTRL_OUTPUT_ENABLE BIT(14) + +struct apple_pwm { + struct pwm_chip chip; + void __iomem *base; + u64 clkrate; +}; + +static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct apple_pwm *fpwm; + u64 on_cycles, off_cycles; + + fpwm = container_of(chip, struct apple_pwm, chip); + if (state->enabled) { + on_cycles = mul_u64_u64_div_u64(fpwm->clkrate, + state->duty_cycle, NSEC_PER_SEC); + off_cycles = mul_u64_u64_div_u64(fpwm->clkrate, + state->period, NSEC_PER_SEC) - on_cycles; + writel(on_cycles, fpwm->base + PWM_ON_CYCLES); + writel(off_cycles, fpwm->base + PWM_OFF_CYCLES); + writel(CTRL_ENABLE | CTRL_OUTPUT_ENABLE | CTRL_UPDATE, + fpwm->base + PWM_CONTROL); + } else { + writel(0, fpwm->base + PWM_CONTROL); + } + return 0; +} + +static void apple_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + struct apple_pwm *fpwm; + u32 on_cycles, off_cycles, ctrl; + + fpwm = container_of(chip, struct apple_pwm, chip); + + ctrl = readl(fpwm->base + PWM_CONTROL); + on_cycles = readl(fpwm->base + PWM_ON_CYCLES); + off_cycles = readl(fpwm->base + PWM_OFF_CYCLES); + + state->enabled = (ctrl & CTRL_ENABLE) && (ctrl & CTRL_OUTPUT_ENABLE); + state->polarity = PWM_POLARITY_NORMAL; + state->duty_cycle = div_u64(on_cycles, fpwm->clkrate) * NSEC_PER_SEC; + state->period = div_u64(off_cycles + on_cycles, fpwm->clkrate) * NSEC_PER_SEC; +} + +static const struct pwm_ops apple_pwm_ops = { + .apply = apple_pwm_apply, + .get_state = apple_pwm_get_state, + .owner = THIS_MODULE, +}; + +static int apple_pwm_probe(struct platform_device *pdev) +{ + struct apple_pwm *pwm; + struct clk *clk; + int ret; + + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); + if (!pwm) + return -ENOMEM; + + pwm->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(pwm->base)) + return PTR_ERR(pwm->base); + + platform_set_drvdata(pdev, pwm); + + clk = devm_clk_get_enabled(&pdev->dev, NULL); + if (IS_ERR(clk)) + return PTR_ERR(clk); + + pwm->clkrate = clk_get_rate(clk); + pwm->chip.dev = &pdev->dev; + pwm->chip.npwm = 1; + pwm->chip.ops = &apple_pwm_ops; + + ret = devm_pwmchip_add(&pdev->dev, &pwm->chip); + return ret; +} + +static const struct of_device_id apple_pwm_of_match[] = { + { .compatible = "apple,s5l-fpwm" }, + {} +}; +MODULE_DEVICE_TABLE(of, apple_pwm_of_match); + +static struct platform_driver apple_pwm_driver = { + .probe = apple_pwm_probe, + .driver = { + .name = "apple-pwm", + .owner = THIS_MODULE, + .of_match_table = apple_pwm_of_match, + }, +}; +module_platform_driver(apple_pwm_driver); + +MODULE_DESCRIPTION("Apple SoC PWM driver"); +MODULE_LICENSE("Dual MIT/GPL");