| Message ID | 20210109180220.121511-1-j.neuschaefer@gmx.net |
|---|---|
| Headers | show |
| Series | Netronix embedded controller driver for Kobo and Tolino ebook readers | expand |
Hello, On Sat, Jan 09, 2021 at 07:02:17PM +0100, Jonathan Neuschäfer wrote: > The Netronix EC provides a PWM output which is used for the backlight > on some ebook readers. This patches adds a driver for the PWM output. > > The .get_state callback is not implemented, because the PWM state can't > be read back from the hardware. There is only very little I would have done differently (only indention which is too minor to make a fuss), so: Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Thanks for your work Uwe
On Sat, Jan 09, 2021 at 07:02:17PM +0100, Jonathan Neuschäfer wrote: > The Netronix EC provides a PWM output which is used for the backlight > on some ebook readers. This patches adds a driver for the PWM output. > > The .get_state callback is not implemented, because the PWM state can't > be read back from the hardware. > > Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> > --- > v7: > - no changes > > v6: > - https://lore.kernel.org/lkml/20201208011000.3060239-5-j.neuschaefer@gmx.net/ > - Move period / duty cycle setting code to a function > - Rename pwmchip_to_priv to ntxec_pwm_from_chip > - Set period and duty cycle only before enabling the output > - Mention that duty=0, enable=1 is assumed not to happen > - Interleave writes to the period and duty cycle registers, to minimize the > window of time that an inconsistent state is configured > > v5: > - https://lore.kernel.org/lkml/20201201011513.1627028-5-j.neuschaefer@gmx.net/ > - Avoid truncation of period and duty cycle to 32 bits > - Make ntxec_pwm_ops const > - Use regmap_multi_reg_write > - Add comment about get_state to ntxec_pwm_ops > - Add comments about non-atomicity of (period, duty cycle) update > > v4: > - https://lore.kernel.org/lkml/20201122222739.1455132-5-j.neuschaefer@gmx.net/ > - Document hardware/driver limitations > - Only accept normal polarity > - Fix a typo ("zone" -> "zero") > - change MAX_PERIOD_NS to 0xffff * 125 > - Clamp period to the maximum rather than returning an error > - Rename private struct pointer to priv > - Rearrage control flow in _probe to save a few lines and a temporary variable > - Add missing MODULE_ALIAS line > - Spell out ODM > > v3: > - https://lore.kernel.org/lkml/20200924192455.2484005-5-j.neuschaefer@gmx.net/ > - Relicense as GPLv2 or later > - Add email address to copyright line > - Remove OF compatible string and don't include linux/of_device.h > - Fix bogus ?: in return line > - Don't use a comma after sentinels > - Avoid ret |= ... pattern > - Move 8-bit register conversion to ntxec.h > > v2: > - https://lore.kernel.org/lkml/20200905133230.1014581-6-j.neuschaefer@gmx.net/ > - Various grammar and style improvements, as suggested by Uwe Kleine-König, > Lee Jones, and Alexandre Belloni > - Switch to regmap > - Prefix registers with NTXEC_REG_ > - Add help text to the Kconfig option > - Use the .apply callback instead of the old API > - Add a #define for the time base (125ns) > - Don't change device state in .probe; this avoids multiple problems > - Rework division and overflow check logic to perform divisions in 32 bits > - Avoid setting duty cycle to zero, to work around a hardware quirk > --- > drivers/pwm/Kconfig | 8 ++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-ntxec.c | 182 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 191 insertions(+) > create mode 100644 drivers/pwm/pwm-ntxec.c Lee, I assume you'll want to pick the whole set up into the MFD tree? If so: Acked-by: Thierry Reding <thierry.reding@gmail.com>
On Mon, 11 Jan 2021, Thierry Reding wrote: > On Sat, Jan 09, 2021 at 07:02:17PM +0100, Jonathan Neuschäfer wrote: > > The Netronix EC provides a PWM output which is used for the backlight > > on some ebook readers. This patches adds a driver for the PWM output. > > > > The .get_state callback is not implemented, because the PWM state can't > > be read back from the hardware. > > > > Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> > > --- > > v7: > > - no changes > > > > v6: > > - https://lore.kernel.org/lkml/20201208011000.3060239-5-j.neuschaefer@gmx.net/ > > - Move period / duty cycle setting code to a function > > - Rename pwmchip_to_priv to ntxec_pwm_from_chip > > - Set period and duty cycle only before enabling the output > > - Mention that duty=0, enable=1 is assumed not to happen > > - Interleave writes to the period and duty cycle registers, to minimize the > > window of time that an inconsistent state is configured > > > > v5: > > - https://lore.kernel.org/lkml/20201201011513.1627028-5-j.neuschaefer@gmx.net/ > > - Avoid truncation of period and duty cycle to 32 bits > > - Make ntxec_pwm_ops const > > - Use regmap_multi_reg_write > > - Add comment about get_state to ntxec_pwm_ops > > - Add comments about non-atomicity of (period, duty cycle) update > > > > v4: > > - https://lore.kernel.org/lkml/20201122222739.1455132-5-j.neuschaefer@gmx.net/ > > - Document hardware/driver limitations > > - Only accept normal polarity > > - Fix a typo ("zone" -> "zero") > > - change MAX_PERIOD_NS to 0xffff * 125 > > - Clamp period to the maximum rather than returning an error > > - Rename private struct pointer to priv > > - Rearrage control flow in _probe to save a few lines and a temporary variable > > - Add missing MODULE_ALIAS line > > - Spell out ODM > > > > v3: > > - https://lore.kernel.org/lkml/20200924192455.2484005-5-j.neuschaefer@gmx.net/ > > - Relicense as GPLv2 or later > > - Add email address to copyright line > > - Remove OF compatible string and don't include linux/of_device.h > > - Fix bogus ?: in return line > > - Don't use a comma after sentinels > > - Avoid ret |= ... pattern > > - Move 8-bit register conversion to ntxec.h > > > > v2: > > - https://lore.kernel.org/lkml/20200905133230.1014581-6-j.neuschaefer@gmx.net/ > > - Various grammar and style improvements, as suggested by Uwe Kleine-König, > > Lee Jones, and Alexandre Belloni > > - Switch to regmap > > - Prefix registers with NTXEC_REG_ > > - Add help text to the Kconfig option > > - Use the .apply callback instead of the old API > > - Add a #define for the time base (125ns) > > - Don't change device state in .probe; this avoids multiple problems > > - Rework division and overflow check logic to perform divisions in 32 bits > > - Avoid setting duty cycle to zero, to work around a hardware quirk > > --- > > drivers/pwm/Kconfig | 8 ++ > > drivers/pwm/Makefile | 1 + > > drivers/pwm/pwm-ntxec.c | 182 ++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 191 insertions(+) > > create mode 100644 drivers/pwm/pwm-ntxec.c > > Lee, I assume you'll want to pick the whole set up into the MFD tree? If > so: Yes, I'll pick this up once we have all the Acks. The Arm parts usually go in separately. > Acked-by: Thierry Reding <thierry.reding@gmail.com> Thanks.
On Sat, 9 Jan 2021 19:02:16 +0100 Jonathan Neuschäfer <j.neuschaefer@gmx.net> wrote: > The Netronix embedded controller is a microcontroller found in some > e-book readers designed by the original design manufacturer Netronix, > Inc. It contains RTC, battery monitoring, system power management, and > PWM functionality. > > This driver implements register access and version detection. > > Third-party hardware documentation is available at: > > https://github.com/neuschaefer/linux/wiki/Netronix-MSP430-embedded-controller > > The EC supports interrupts, but the driver doesn't make use of them so > far. > > Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> > Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org> > --- > v7: > - Add #define for version number (suggested by Lee Jones). > > v6: > - https://lore.kernel.org/lkml/20201208011000.3060239-4-j.neuschaefer@gmx.net/ > - Add Lee Jones' ACK > > v5: > - no changes > > v4: > - https://lore.kernel.org/lkml/20201122222739.1455132-4-j.neuschaefer@gmx.net/ > - include asm/unaligned.h after linux/* > - Use put_unaligned_be16 instead of open-coded big-endian packing > - Clarify that 0x90=0xff00 causes an error in downstream kernel too > - Add commas after non-sentinel positions > - ntxec.h: declare structs device and regmap > - Replace WARN_ON usage and add comments to explain errors > - Replace dev_alert with dev_warn when the result isn't handled > - Change subdevice registration error message to dev_err > - Declare ntxec_reg8 as returning __be16 > - Restructure version detection code > - Spell out ODM > > v3: > - https://lore.kernel.org/lkml/20200924192455.2484005-4-j.neuschaefer@gmx.net/ > - Add (EC) to CONFIG_MFD_NTXEC prompt > - Relicense as GPLv2 or later > - Add email address to copyright line > - remove empty lines in ntxec_poweroff and ntxec_restart functions > - Split long lines > - Remove 'Install ... handler' comments > - Make naming of struct i2c_client parameter consistent > - Remove struct ntxec_info > - Rework 'depends on' lines in Kconfig, hard-depend on I2C, select REGMAP_I2C and > MFD_CORE > - Register subdevices via mfd_cells > - Move 8-bit register conversion to ntxec.h > > v2: > - https://lore.kernel.org/lkml/20200905133230.1014581-4-j.neuschaefer@gmx.net/ > - Add a description of the device to the patch text > - Unify spelling as 'Netronix embedded controller'. > 'Netronix' is the proper name of the manufacturer, but 'embedded controller' > is just a label that I have assigned to the device. > - Switch to regmap, avoid regmap use in poweroff and reboot handlers. > Inspired by cf84dc0bb40f4 ("mfd: rn5t618: Make restart handler atomic safe") > - Use a list of known-working firmware versions instead of checking for a > known-incompatible version > - Prefix registers with NTXEC_REG_ > - Define register values as constants > - Various style cleanups as suggested by Lee Jones > - Don't align = signs in struct initializers [Uwe Kleine-König] > - Don't use dev_dbg for an error message > - Explain sleep in poweroff handler > - Remove (struct ntxec).client > - Switch to .probe_new in i2c driver > - Add .remove callback > - Make CONFIG_MFD_NTXEC a tristate option > --- > drivers/mfd/Kconfig | 11 ++ > drivers/mfd/Makefile | 1 + > drivers/mfd/ntxec.c | 216 ++++++++++++++++++++++++++++++++++++++ > include/linux/mfd/ntxec.h | 37 +++++++ > 4 files changed, 265 insertions(+) > create mode 100644 drivers/mfd/ntxec.c > create mode 100644 include/linux/mfd/ntxec.h > > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig > index bdfce7b156216..4280bcd47ec7d 100644 > --- a/drivers/mfd/Kconfig > +++ b/drivers/mfd/Kconfig > @@ -976,6 +976,17 @@ config MFD_VIPERBOARD > You need to select the mfd cell drivers separately. > The drivers do not support all features the board exposes. > > +config MFD_NTXEC > + tristate "Netronix embedded controller (EC)" > + depends on OF || COMPILE_TEST > + depends on I2C > + select REGMAP_I2C > + select MFD_CORE > + help > + Say yes here if you want to support the embedded controller found in > + certain e-book readers designed by the original design manufacturer > + Netronix. > + > config MFD_RETU > tristate "Nokia Retu and Tahvo multi-function device" > select MFD_CORE > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile > index 14fdb188af022..948a3bf8e3e57 100644 > --- a/drivers/mfd/Makefile > +++ b/drivers/mfd/Makefile > @@ -219,6 +219,7 @@ obj-$(CONFIG_MFD_INTEL_PMC_BXT) += intel_pmc_bxt.o > obj-$(CONFIG_MFD_INTEL_PMT) += intel_pmt.o > obj-$(CONFIG_MFD_PALMAS) += palmas.o > obj-$(CONFIG_MFD_VIPERBOARD) += viperboard.o > +obj-$(CONFIG_MFD_NTXEC) += ntxec.o > obj-$(CONFIG_MFD_RC5T583) += rc5t583.o rc5t583-irq.o > obj-$(CONFIG_MFD_RK808) += rk808.o > obj-$(CONFIG_MFD_RN5T618) += rn5t618.o > diff --git a/drivers/mfd/ntxec.c b/drivers/mfd/ntxec.c > new file mode 100644 > index 0000000000000..22ed2ef0669cb > --- /dev/null > +++ b/drivers/mfd/ntxec.c > @@ -0,0 +1,216 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * The Netronix embedded controller is a microcontroller found in some > + * e-book readers designed by the original design manufacturer Netronix, Inc. > + * It contains RTC, battery monitoring, system power management, and PWM > + * functionality. > + * > + * This driver implements register access, version detection, and system > + * power-off/reset. > + * > + * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net> > + */ > + > +#include <linux/delay.h> > +#include <linux/errno.h> > +#include <linux/i2c.h> > +#include <linux/mfd/core.h> > +#include <linux/mfd/ntxec.h> > +#include <linux/module.h> > +#include <linux/pm.h> > +#include <linux/reboot.h> > +#include <linux/regmap.h> > +#include <linux/types.h> > +#include <asm/unaligned.h> > + > +#define NTXEC_REG_VERSION 0x00 > +#define NTXEC_REG_POWEROFF 0x50 > +#define NTXEC_REG_POWERKEEP 0x70 > +#define NTXEC_REG_RESET 0x90 > + > +#define NTXEC_POWEROFF_VALUE 0x0100 > +#define NTXEC_POWERKEEP_VALUE 0x0800 > +#define NTXEC_RESET_VALUE 0xff00 > + > +static struct i2c_client *poweroff_restart_client; > + > +static void ntxec_poweroff(void) > +{ > + int res; > + u8 buf[3] = { NTXEC_REG_POWEROFF }; > + struct i2c_msg msgs[] = { > + { > + .addr = poweroff_restart_client->addr, > + .flags = 0, > + .len = sizeof(buf), > + .buf = buf, > + }, > + }; > + > + put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1); > + > + res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs)); > + if (res < 0) > + dev_warn(&poweroff_restart_client->dev, > + "Failed to power off (err = %d)\n", res); > + > + /* > + * The time from the register write until the host CPU is powered off > + * has been observed to be about 2.5 to 3 seconds. Sleep long enough to > + * safely avoid returning from the poweroff handler. > + */ > + msleep(5000); > +} > + > +static int ntxec_restart(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + int res; > + u8 buf[3] = { NTXEC_REG_RESET }; > + /* > + * NOTE: The lower half of the reset value is not sent, because sending > + * it causes an I2C error. (The reset handler in the downstream driver > + * does send the full two-byte value, but doesn't check the result). > + */ > + struct i2c_msg msgs[] = { > + { > + .addr = poweroff_restart_client->addr, > + .flags = 0, > + .len = sizeof(buf) - 1, > + .buf = buf, > + }, > + }; > + > + put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1); > + > + res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs)); > + if (res < 0) > + dev_warn(&poweroff_restart_client->dev, > + "Failed to restart (err = %d)\n", res); > + > + return NOTIFY_DONE; > +} > + > +static struct notifier_block ntxec_restart_handler = { > + .notifier_call = ntxec_restart, > + .priority = 128, > +}; > + > +static const struct regmap_config regmap_config = { > + .name = "ntxec", > + .reg_bits = 8, > + .val_bits = 16, > + .cache_type = REGCACHE_NONE, > + .val_format_endian = REGMAP_ENDIAN_BIG, > +}; > + > +static const struct mfd_cell ntxec_subdevices[] = { > + { .name = "ntxec-rtc" }, > + { .name = "ntxec-pwm" }, > +}; > + > +static int ntxec_probe(struct i2c_client *client) > +{ > + struct ntxec *ec; > + unsigned int version; > + int res; > + > + ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL); > + if (!ec) > + return -ENOMEM; > + > + ec->dev = &client->dev; > + > + ec->regmap = devm_regmap_init_i2c(client, ®map_config); > + if (IS_ERR(ec->regmap)) { > + dev_err(ec->dev, "Failed to set up regmap for device\n"); > + return res; > + } > + > + /* Determine the firmware version */ > + res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version); > + if (res < 0) { > + dev_err(ec->dev, "Failed to read firmware version number\n"); > + return res; > + } > + > + /* Bail out if we encounter an unknown firmware version */ > + switch (version) { > + case NTXEC_VERSION_KOBO_AURA: > + break; > + default: > + dev_err(ec->dev, > + "Netronix embedded controller version %04x is not supported.\n", > + version); > + return -ENODEV; > + } > + > + dev_info(ec->dev, > + "Netronix embedded controller version %04x detected.\n", version); > + > + if (of_device_is_system_power_controller(ec->dev->of_node)) { > + /* > + * Set the 'powerkeep' bit. This is necessary on some boards > + * in order to keep the system running. > + */ > + res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP, > + NTXEC_POWERKEEP_VALUE); > + if (res < 0) > + return res; > + > + if (poweroff_restart_client) > + /* > + * Another instance of the driver already took > + * poweroff/restart duties. > + */ > + dev_err(ec->dev, "poweroff_restart_client already assigned\n"); > + else > + poweroff_restart_client = client; > + > + if (pm_power_off) > + /* Another driver already registered a poweroff handler. */ > + dev_err(ec->dev, "pm_power_off already assigned\n"); > + else > + pm_power_off = ntxec_poweroff; > + > + res = register_restart_handler(&ntxec_restart_handler); > + if (res) > + dev_err(ec->dev, > + "Failed to register restart handler: %d\n", res); > + } > + > + i2c_set_clientdata(client, ec); > + > + res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, ntxec_subdevices, > + ARRAY_SIZE(ntxec_subdevices), NULL, 0, NULL); > + if (res) > + dev_err(ec->dev, "Failed to add subdevices: %d\n", res); > + > + return res; > +} > + > +static int ntxec_remove(struct i2c_client *client) > +{ > + if (client == poweroff_restart_client) { > + poweroff_restart_client = NULL; > + pm_power_off = NULL; > + unregister_restart_handler(&ntxec_restart_handler); > + } > + > + return 0; > +} > + > +static const struct of_device_id of_ntxec_match_table[] = { > + { .compatible = "netronix,ntxec", }, > + {} > +}; > + MODULE_DEVICE_TABLE? > +static struct i2c_driver ntxec_driver = { > + .driver = { > + .name = "ntxec", > + .of_match_table = of_ntxec_match_table, > + }, > + .probe_new = ntxec_probe, > + .remove = ntxec_remove, > +}; > +module_i2c_driver(ntxec_driver); MODULE_LICENSE()? modpost moans about that here. Regards, Andreas
On Sat, 9 Jan 2021 19:02:17 +0100 Jonathan Neuschäfer <j.neuschaefer@gmx.net> wrote: > The Netronix EC provides a PWM output which is used for the backlight > on some ebook readers. This patches adds a driver for the PWM output. > > The .get_state callback is not implemented, because the PWM state can't > be read back from the hardware. > > Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> > --- > v7: > - no changes > > v6: > - https://lore.kernel.org/lkml/20201208011000.3060239-5-j.neuschaefer@gmx.net/ > - Move period / duty cycle setting code to a function > - Rename pwmchip_to_priv to ntxec_pwm_from_chip > - Set period and duty cycle only before enabling the output > - Mention that duty=0, enable=1 is assumed not to happen > - Interleave writes to the period and duty cycle registers, to minimize the > window of time that an inconsistent state is configured > > v5: > - https://lore.kernel.org/lkml/20201201011513.1627028-5-j.neuschaefer@gmx.net/ > - Avoid truncation of period and duty cycle to 32 bits > - Make ntxec_pwm_ops const > - Use regmap_multi_reg_write > - Add comment about get_state to ntxec_pwm_ops > - Add comments about non-atomicity of (period, duty cycle) update > > v4: > - https://lore.kernel.org/lkml/20201122222739.1455132-5-j.neuschaefer@gmx.net/ > - Document hardware/driver limitations > - Only accept normal polarity > - Fix a typo ("zone" -> "zero") > - change MAX_PERIOD_NS to 0xffff * 125 > - Clamp period to the maximum rather than returning an error > - Rename private struct pointer to priv > - Rearrage control flow in _probe to save a few lines and a temporary variable > - Add missing MODULE_ALIAS line > - Spell out ODM > > v3: > - https://lore.kernel.org/lkml/20200924192455.2484005-5-j.neuschaefer@gmx.net/ > - Relicense as GPLv2 or later > - Add email address to copyright line > - Remove OF compatible string and don't include linux/of_device.h > - Fix bogus ?: in return line > - Don't use a comma after sentinels > - Avoid ret |= ... pattern > - Move 8-bit register conversion to ntxec.h > > v2: > - https://lore.kernel.org/lkml/20200905133230.1014581-6-j.neuschaefer@gmx.net/ > - Various grammar and style improvements, as suggested by Uwe Kleine-König, > Lee Jones, and Alexandre Belloni > - Switch to regmap > - Prefix registers with NTXEC_REG_ > - Add help text to the Kconfig option > - Use the .apply callback instead of the old API > - Add a #define for the time base (125ns) > - Don't change device state in .probe; this avoids multiple problems > - Rework division and overflow check logic to perform divisions in 32 bits > - Avoid setting duty cycle to zero, to work around a hardware quirk > --- > drivers/pwm/Kconfig | 8 ++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-ntxec.c | 182 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 191 insertions(+) > create mode 100644 drivers/pwm/pwm-ntxec.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index 0937e1c047acb..a2830b8832b97 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -393,6 +393,14 @@ config PWM_MXS > To compile this driver as a module, choose M here: the module > will be called pwm-mxs. > > +config PWM_NTXEC > + tristate "Netronix embedded controller PWM support" > + depends on MFD_NTXEC > + help > + Say yes here if you want to support the PWM output of the embedded > + controller found in certain e-book readers designed by the original > + design manufacturer Netronix. > + > config PWM_OMAP_DMTIMER > tristate "OMAP Dual-Mode Timer PWM support" > depends on OF > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index 18b89d7fd092a..7d97eb595bbef 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -35,6 +35,7 @@ obj-$(CONFIG_PWM_MESON) += pwm-meson.o > obj-$(CONFIG_PWM_MEDIATEK) += pwm-mediatek.o > obj-$(CONFIG_PWM_MTK_DISP) += pwm-mtk-disp.o > obj-$(CONFIG_PWM_MXS) += pwm-mxs.o > +obj-$(CONFIG_PWM_NTXEC) += pwm-ntxec.o > obj-$(CONFIG_PWM_OMAP_DMTIMER) += pwm-omap-dmtimer.o > obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o > obj-$(CONFIG_PWM_PXA) += pwm-pxa.o > diff --git a/drivers/pwm/pwm-ntxec.c b/drivers/pwm/pwm-ntxec.c > new file mode 100644 > index 0000000000000..1db30a6caa3ad > --- /dev/null > +++ b/drivers/pwm/pwm-ntxec.c > @@ -0,0 +1,182 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * The Netronix embedded controller is a microcontroller found in some > + * e-book readers designed by the original design manufacturer Netronix, Inc. > + * It contains RTC, battery monitoring, system power management, and PWM > + * functionality. > + * > + * This driver implements PWM output. > + * > + * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net> > + * > + * Limitations: > + * - The get_state callback is not implemented, because the current state of > + * the PWM output can't be read back from the hardware. > + * - The hardware can only generate normal polarity output. > + * - The period and duty cycle can't be changed together in one atomic action. > + */ > + > +#include <linux/mfd/ntxec.h> > +#include <linux/module.h> > +#include <linux/platform_device.h> > +#include <linux/pwm.h> > +#include <linux/regmap.h> > +#include <linux/types.h> > + > +struct ntxec_pwm { > + struct device *dev; > + struct ntxec *ec; > + struct pwm_chip chip; > +}; > + > +static struct ntxec_pwm *ntxec_pwm_from_chip(struct pwm_chip *chip) > +{ > + return container_of(chip, struct ntxec_pwm, chip); > +} > + > +#define NTXEC_REG_AUTO_OFF_HI 0xa1 > +#define NTXEC_REG_AUTO_OFF_LO 0xa2 > +#define NTXEC_REG_ENABLE 0xa3 > +#define NTXEC_REG_PERIOD_LOW 0xa4 > +#define NTXEC_REG_PERIOD_HIGH 0xa5 > +#define NTXEC_REG_DUTY_LOW 0xa6 > +#define NTXEC_REG_DUTY_HIGH 0xa7 > + > +/* > + * The time base used in the EC is 8MHz, or 125ns. Period and duty cycle are > + * measured in this unit. > + */ > +#define TIME_BASE_NS 125 > + > +/* > + * The maximum input value (in nanoseconds) is determined by the time base and > + * the range of the hardware registers that hold the converted value. > + * It fits into 32 bits, so we can do our calculations in 32 bits as well. > + */ > +#define MAX_PERIOD_NS (TIME_BASE_NS * 0xffff) > + > +static int ntxec_pwm_set_raw_period_and_duty_cycle(struct pwm_chip *chip, > + int period, int duty) > +{ > + struct ntxec_pwm *priv = ntxec_pwm_from_chip(chip); > + > + /* > + * Changes to the period and duty cycle take effect as soon as the > + * corresponding low byte is written, so the hardware may be configured > + * to an inconsistent state after the period is written and before the > + * duty cycle is fully written. If, in such a case, the old duty cycle > + * is longer than the new period, the EC may output 100% for a moment. > + * > + * To minimize the time between the changes to period and duty cycle > + * taking effect, the writes are interleaved. > + */ > + > + struct reg_sequence regs[] = { > + { NTXEC_REG_PERIOD_HIGH, ntxec_reg8(period >> 8) }, > + { NTXEC_REG_DUTY_HIGH, ntxec_reg8(duty >> 8) }, > + { NTXEC_REG_PERIOD_LOW, ntxec_reg8(period) }, > + { NTXEC_REG_DUTY_LOW, ntxec_reg8(duty) }, > + }; > + > + return regmap_multi_reg_write(priv->ec->regmap, regs, ARRAY_SIZE(regs)); > +} > + > +static int ntxec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm_dev, > + const struct pwm_state *state) > +{ > + struct ntxec_pwm *priv = ntxec_pwm_from_chip(chip); > + unsigned int period, duty; > + int res; > + > + if (state->polarity != PWM_POLARITY_NORMAL) > + return -EINVAL; > + > + period = min_t(u64, state->period, MAX_PERIOD_NS); > + duty = min_t(u64, state->duty_cycle, period); > + > + period /= TIME_BASE_NS; > + duty /= TIME_BASE_NS; > + > + /* > + * Writing a duty cycle of zero puts the device into a state where > + * writing a higher duty cycle doesn't result in the brightness that it > + * usually results in. This can be fixed by cycling the ENABLE register. > + * > + * As a workaround, write ENABLE=0 when the duty cycle is zero. > + * The case that something has previously set the duty cycle to zero > + * but ENABLE=1, is not handled. > + */ > + if (state->enabled && duty != 0) { > + res = ntxec_pwm_set_raw_period_and_duty_cycle(chip, period, duty); > + if (res) > + return res; > + > + res = regmap_write(priv->ec->regmap, NTXEC_REG_ENABLE, ntxec_reg8(1)); > + if (res) > + return res; > + > + /* Disable the auto-off timer */ > + res = regmap_write(priv->ec->regmap, NTXEC_REG_AUTO_OFF_HI, ntxec_reg8(0xff)); > + if (res) > + return res; > + > + return regmap_write(priv->ec->regmap, NTXEC_REG_AUTO_OFF_LO, ntxec_reg8(0xff)); > + } else { > + return regmap_write(priv->ec->regmap, NTXEC_REG_ENABLE, ntxec_reg8(0)); > + } > +} > + > +static const struct pwm_ops ntxec_pwm_ops = { > + .owner = THIS_MODULE, > + .apply = ntxec_pwm_apply, > + /* > + * No .get_state callback, because the current state cannot be read > + * back from the hardware. > + */ > +}; > + > +static int ntxec_pwm_probe(struct platform_device *pdev) > +{ > + struct ntxec *ec = dev_get_drvdata(pdev->dev.parent); > + struct ntxec_pwm *priv; > + struct pwm_chip *chip; > + > + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); > + if (!priv) > + return -ENOMEM; > + > + priv->ec = ec; > + priv->dev = &pdev->dev; > + > + platform_set_drvdata(pdev, priv); > + > + chip = &priv->chip; > + chip->dev = &pdev->dev; Hmm, I needed chip->dev = &pdev->dev.parent to use the backlight example in patch 2/7. Not sure what the correct solution is. Maybe the pwm deserves its own devicetree node. Regards, Andreas
On Tue, 12 Jan 2021, Andreas Kemnade wrote: > On Sat, 9 Jan 2021 19:02:16 +0100 > Jonathan Neuschäfer <j.neuschaefer@gmx.net> wrote: > > > The Netronix embedded controller is a microcontroller found in some > > e-book readers designed by the original design manufacturer Netronix, > > Inc. It contains RTC, battery monitoring, system power management, and > > PWM functionality. > > > > This driver implements register access and version detection. > > > > Third-party hardware documentation is available at: > > > > https://github.com/neuschaefer/linux/wiki/Netronix-MSP430-embedded-controller > > > > The EC supports interrupts, but the driver doesn't make use of them so > > far. > > > > Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net> > > Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org> [...] > > +static const struct of_device_id of_ntxec_match_table[] = { > > + { .compatible = "netronix,ntxec", }, > > + {} > > +}; > > + > MODULE_DEVICE_TABLE? > > > +static struct i2c_driver ntxec_driver = { > > + .driver = { > > + .name = "ntxec", > > + .of_match_table = of_ntxec_match_table, > > + }, > > + .probe_new = ntxec_probe, > > + .remove = ntxec_remove, > > +}; > > +module_i2c_driver(ntxec_driver); > > MODULE_LICENSE()? > > modpost moans about that here. Andreas, would you be kind enough to snip/trim your replies in future please. It would save a *lot* of people a little bit of time (which adds up fast). TIA.
On Tue, 12 Jan 2021 20:39:02 +0100 Andreas Kemnade <andreas@kemnade.info> wrote: [...] > > +static int ntxec_pwm_probe(struct platform_device *pdev) > > +{ > > + struct ntxec *ec = dev_get_drvdata(pdev->dev.parent); > > + struct ntxec_pwm *priv; > > + struct pwm_chip *chip; > > + > > + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); > > + if (!priv) > > + return -ENOMEM; > > + > > + priv->ec = ec; > > + priv->dev = &pdev->dev; > > + > > + platform_set_drvdata(pdev, priv); > > + > > + chip = &priv->chip; > > + chip->dev = &pdev->dev; > > Hmm, I needed > chip->dev = &pdev->dev.parent to use the backlight example > in patch 2/7. > Not sure what the correct solution is. Maybe the pwm deserves its own > devicetree node. > probably just assigning the node from the parent. pdev->dev.of_node = pdev->dev.parent->of_node; Regards, Andreas
On Tue, Jan 12, 2021 at 08:36:49PM +0100, Andreas Kemnade wrote: > On Sat, 9 Jan 2021 19:02:16 +0100 > Jonathan Neuschäfer <j.neuschaefer@gmx.net> wrote: [...] > > +static const struct of_device_id of_ntxec_match_table[] = { > > + { .compatible = "netronix,ntxec", }, > > + {} > > +}; > > + > MODULE_DEVICE_TABLE? Yes, good idea. > > +static struct i2c_driver ntxec_driver = { > > + .driver = { > > + .name = "ntxec", > > + .of_match_table = of_ntxec_match_table, > > + }, > > + .probe_new = ntxec_probe, > > + .remove = ntxec_remove, > > +}; > > +module_i2c_driver(ntxec_driver); > > MODULE_LICENSE()? > > modpost moans about that here. I forgot those. Thanks for noticing. I'll add the MODULE_ lines in v8. Thanks, Jonathan
On Wed, Jan 13, 2021 at 11:46:45PM +0100, Andreas Kemnade wrote: > On Tue, 12 Jan 2021 20:39:02 +0100 > Andreas Kemnade <andreas@kemnade.info> wrote: > > [...] > > > +static int ntxec_pwm_probe(struct platform_device *pdev) [...] > > Hmm, I needed > > chip->dev = &pdev->dev.parent to use the backlight example > > in patch 2/7. > > Not sure what the correct solution is. Maybe the pwm deserves its own > > devicetree node. > > > probably just assigning the node from the parent. > > pdev->dev.of_node = pdev->dev.parent->of_node; Ah, good catch, thanks. This works, I'll add it to the next version. Jonathan