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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-04-29 01:59:13 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-04-29 01:59:13 +0300 |
commit | 71a5cc28e88b0db69c3f83d4061ad4cc684af09f (patch) | |
tree | 3cc40d902e7cba992c27c946f69ef65fc7d2a807 /drivers/pwm/pwm-ntxec.c | |
parent | be18cd1fcae2ed7db58d92d20733dfa8aa0a5173 (diff) | |
parent | f9386c91574fe6da9f4fca9a47734816b0db0019 (diff) | |
download | linux-71a5cc28e88b0db69c3f83d4061ad4cc684af09f.tar.xz |
Merge tag 'mfd-next-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd
Pull MFD updates from Lee Jones:
"Core Framework:
- Add support for Software Nodes to MFD Core
- Remove support for Device Properties from MFD Core
- Use standard APIs in MFD Core
New Drivers:
- Add support for ROHM BD9576MUF and BD9573MUF PMICs
- Add support for Netronix Embedded Controller, PWM and RTC
- Add support for Actions Semi ATC260x PMICs and OnKey
New Device Support:
- Add support for DG1 PCIe Graphics Card to Intel PMT
- Add support for ROHM BD71815 PMIC to ROHM BD71828
- Add support for Tolino Shine 2 HD to Netronix Embedded Controller
- Add support for AX10 BMC Secure Updates to Intel M10 BMC
Removed Device Support:
- Remove Arizona Extcon support from MFD
- Remove ST-E AB8500 Power Supply code from MFD
- Remove AB3100 altogether
New Functionality:
- Add support for SMBus and I2C modes to Dialog DA9063
- Switch to using Software Nodes in Intel (various)
New/converted Device Tree bindings:
- rohm bd71815-pmic, rohm bd9576-pmic, netronix ntxec, actions
atc260x, ricoh rn5t618, qcom pm8xxx
- Fix-ups:
- Fix error handling/path; intel_pmt
- Simplify code; rohm-bd718x7, ab8500-core, intel-m10-bmc
- Trivial clean-ups (reordering, spelling); rohm-generic, rn5t618,
max8997
- Use correct data-type; db8500-prcmu
- Remove superfluous code; lp87565, intel_quark_i2c_gpi, lpc_sch, twl
- Use generic APIs/defines; lm3533-core, intel_quark_i2c_gpio
- Regmap related fix-ups; intel-m10-bmc, sec-core
- Reorder resource freeing during remove; intel_quark_i2c_gpio
- Make table indexing more robust; intel_quark_i2c_gpio
- Fix reference imbalances; arizona-irq
- Staticify and (un)constify things; arizona-spi, stmpe, ene-kb3930,
intel-lpss-acpi, intel-lpss-pci, atc260x-i2c, intel_quark_i2c_gpio
Bug Fixes:
- Fix incorrect (register) values; intel-m10-bmc
- Kconfig related fixes; ABX500_CORE
- Do not clear the Auto Reload Register; stm32-timers"
* tag 'mfd-next-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd: (84 commits)
mfd: intel-m10-bmc: Add support for MAX10 BMC Secure Updates
Revert "mfd: max8997: Add of_compatible to Extcon and Charger mfd_cell"
mfd: twl: Remove unused inline function twl4030charger_usb_en()
dt-bindings: mfd: Convert pm8xxx bindings to yaml
dt-bindings: mfd: Add compatible for pmk8350 rtc
i2c: designware: Get rid of legacy platform data
mfd: intel_quark_i2c_gpio: Convert I²C to use software nodes
mfd: lpc_sch: Partially revert "Add support for Intel Quark X1000"
mfd: arizona: Fix rumtime PM imbalance on error
mfd: max8997: Replace 8998 with 8997
mfd: core: Use acpi_find_child_device() for child devices lookup
mfd: intel_quark_i2c_gpio: Don't play dirty trick with const
mfd: intel_quark_i2c_gpio: Enable MSI interrupt
mfd: intel_quark_i2c_gpio: Reuse BAR definitions for MFD cell indexing
mfd: ntxec: Support for EC in Tolino Shine 2 HD
mfd: stm32-timers: Avoid clearing auto reload register
mfd: intel_quark_i2c_gpio: Replace I²C speeds with descriptive definitions
mfd: intel_quark_i2c_gpio: Remove unused struct device member
mfd: intel_quark_i2c_gpio: Unregister resources in reversed order
mfd: Kconfig: ABX500_CORE should depend on ARCH_U8500
...
Diffstat (limited to 'drivers/pwm/pwm-ntxec.c')
-rw-r--r-- | drivers/pwm/pwm-ntxec.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-ntxec.c b/drivers/pwm/pwm-ntxec.c new file mode 100644 index 000000000000..50c454c553c4 --- /dev/null +++ b/drivers/pwm/pwm-ntxec.c @@ -0,0 +1,184 @@ +// 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; + + pdev->dev.of_node = pdev->dev.parent->of_node; + + 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; + chip->ops = &ntxec_pwm_ops; + chip->base = -1; + chip->npwm = 1; + + return pwmchip_add(chip); +} + +static int ntxec_pwm_remove(struct platform_device *pdev) +{ + struct ntxec_pwm *priv = platform_get_drvdata(pdev); + struct pwm_chip *chip = &priv->chip; + + return pwmchip_remove(chip); +} + +static struct platform_driver ntxec_pwm_driver = { + .driver = { + .name = "ntxec-pwm", + }, + .probe = ntxec_pwm_probe, + .remove = ntxec_pwm_remove, +}; +module_platform_driver(ntxec_pwm_driver); + +MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>"); +MODULE_DESCRIPTION("PWM driver for Netronix EC"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ntxec-pwm"); |