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Mon, 6 Jan 2020 00:48:03 +0000 Received: from localhost.localdomain (136.49.227.119) by SN4PR0701CA0020.namprd07.prod.outlook.com (2603:10b6:803:28::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.20.2602.13 via Frontend Transport; Mon, 6 Jan 2020 00:48:02 +0000 From: Jeff LaBundy To: "lee.jones@linaro.org" , "dmitry.torokhov@gmail.com" , "thierry.reding@gmail.com" , "jic23@kernel.org" , "devicetree@vger.kernel.org" CC: "linux-input@vger.kernel.org" , "u.kleine-koenig@pengutronix.de" , "linux-pwm@vger.kernel.org" , "knaack.h@gmx.de" , "lars@metafoo.de" , "pmeerw@pmeerw.net" , "linux-iio@vger.kernel.org" , "robh+dt@kernel.org" , "mark.rutland@arm.com" , Jeff LaBundy Subject: [PATCH v3 4/7] pwm: Add support for Azoteq IQS620A PWM generator Thread-Topic: [PATCH v3 4/7] pwm: Add support for Azoteq IQS620A PWM generator Thread-Index: AQHVxCrzh4C7ONAGT0GQryJS4hKCGA== Date: Mon, 6 Jan 2020 00:48:02 +0000 Message-ID: <1578271620-2159-5-git-send-email-jeff@labundy.com> References: <1578271620-2159-1-git-send-email-jeff@labundy.com> In-Reply-To: <1578271620-2159-1-git-send-email-jeff@labundy.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: SN4PR0701CA0020.namprd07.prod.outlook.com (2603:10b6:803:28::30) To SN6PR08MB5053.namprd08.prod.outlook.com (2603:10b6:805:78::25) authentication-results: spf=none (sender IP is ) smtp.mailfrom=jeff@labundy.com; 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x-microsoft-antispam-message-info: 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 MIME-Version: 1.0 X-OriginatorOrg: labundy.com X-MS-Exchange-CrossTenant-Network-Message-Id: eaf285ea-c90c-44a7-215a-08d7924215cf X-MS-Exchange-CrossTenant-originalarrivaltime: 06 Jan 2020 00:48:02.9426 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 00b69d09-acab-4585-aca7-8fb7c6323e6f X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: vY+7qqqh+uLDSthVw+THmCcYFltymWlixdWl75wP7m8G7dQEiajivDZJxkRop1VOvz8qcwhYTZy/e02mrUYKyw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR08MB4175 Sender: linux-input-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org This patch adds support for the Azoteq IQS620A, capable of generating a 1-kHz PWM output with duty cycle between ~0.4% and 100% (inclusive). Signed-off-by: Jeff LaBundy --- Changes in v3: - Updated the commit message to say "~0.4%" instead of "0.4%" - Clarified the effect of duty cycle and state changes in the 'Limitations' section and added a restriction regarding 0% duty cycle - Added a comment in iqs620_pwm_apply to explain how duty cycle is derived - Updated iqs620_pwm_apply to disable the output first and enable it last to prevent temporarily driving a stale duty cycle - Rounded the calculation for duty cycle up and down in iqs620_pwm_get_state and iqs620_pwm_apply, respectively - Added a comment in iqs620_pwm_get_state to explain what it reports follow- ing requests to set duty cycle to 0% - Added a lock to prevent back-to-back access of IQS620_PWR_SETTINGS_PWM_OUT and IQS620_PWM_DUTY_CYCLE from being interrupted - Updated iqs620_pwm_notifier to reference pwm->state directly as opposed to calling pwm_get_state - Moved notifier unregistration back to a device-managed action - Added a completion to prevent iqs620_pwm_notifier from referencing the pwm_chip structure until it has been initialized by pwmchip_add Changes in v2: - Merged 'Copyright' and 'Author' lines into one in introductory comments - Added 'Limitations' section to introductory comments - Replaced 'error' with 'ret' throughout - Added const qualifier to state argument of iqs620_pwm_apply and removed all modifications to the variable's contents - Updated iqs620_pwm_apply to return -ENOTSUPP or -EINVAL if the requested polarity is inverted or the requested period is below 1 ms, respectively - Updated iqs620_pwm_apply to disable the PWM output if duty cycle is zero - Added iqs620_pwm_get_state - Eliminated tabbed alignment of pwm_ops and platform_driver struct members - Moved notifier unregistration to already present iqs620_pwm_remove, which eliminated the need for a device-managed action and ready flag - Added a comment in iqs620_pwm_probe to explain the order of operations - Changed Kconfig "depends on" logic to MFD_IQS62X || COMPILE_TEST drivers/pwm/Kconfig | 10 ++ drivers/pwm/Makefile | 1 + drivers/pwm/pwm-iqs620a.c | 254 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 265 insertions(+) create mode 100644 drivers/pwm/pwm-iqs620a.c -- 2.7.4 diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index bd21655..60bcf6c 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -222,6 +222,16 @@ config PWM_IMX_TPM To compile this driver as a module, choose M here: the module will be called pwm-imx-tpm. +config PWM_IQS620A + tristate "Azoteq IQS620A PWM support" + depends on MFD_IQS62X || COMPILE_TEST + help + Generic PWM framework driver for the Azoteq IQS620A multi-function + sensor. + + To compile this driver as a module, choose M here: the module will + be called pwm-iqs620a. + config PWM_JZ4740 tristate "Ingenic JZ47xx PWM support" depends on MACH_INGENIC diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index 9a47507..a59c710 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -20,6 +20,7 @@ obj-$(CONFIG_PWM_IMG) += pwm-img.o obj-$(CONFIG_PWM_IMX1) += pwm-imx1.o obj-$(CONFIG_PWM_IMX27) += pwm-imx27.o obj-$(CONFIG_PWM_IMX_TPM) += pwm-imx-tpm.o +obj-$(CONFIG_PWM_IQS620A) += pwm-iqs620a.o obj-$(CONFIG_PWM_JZ4740) += pwm-jz4740.o obj-$(CONFIG_PWM_LP3943) += pwm-lp3943.o obj-$(CONFIG_PWM_LPC18XX_SCT) += pwm-lpc18xx-sct.o diff --git a/drivers/pwm/pwm-iqs620a.c b/drivers/pwm/pwm-iqs620a.c new file mode 100644 index 0000000..ee5d8b5 --- /dev/null +++ b/drivers/pwm/pwm-iqs620a.c @@ -0,0 +1,254 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Azoteq IQS620A PWM Generator + * + * Copyright (C) 2019 Jeff LaBundy + * + * Limitations: + * - The period is fixed to 1 ms and is generated continuously despite changes + * to the duty cycle or enable/disable state. + * - Changes to the duty cycle or enable/disable state take effect immediately + * and may result in a glitch during the period in which the change is made. + * - The device cannot generate a 0% duty cycle. For duty cycles below 1 / 256 + * ms, the output is disabled and relies upon an external pull-down resistor + * to hold the GPIO3/LTX pin low. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define IQS620_PWR_SETTINGS 0xD2 +#define IQS620_PWR_SETTINGS_PWM_OUT BIT(7) + +#define IQS620_PWM_DUTY_CYCLE 0xD8 + +#define IQS620_PWM_PERIOD_NS 1000000 + +struct iqs620_pwm_private { + struct iqs62x_core *iqs62x; + struct pwm_chip chip; + struct notifier_block notifier; + struct completion chip_ready; + struct mutex lock; +}; + +static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct iqs620_pwm_private *iqs620_pwm; + struct iqs62x_core *iqs62x; + int duty_scale, ret; + + if (state->polarity != PWM_POLARITY_NORMAL) + return -ENOTSUPP; + + if (state->period < IQS620_PWM_PERIOD_NS) + return -EINVAL; + + iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip); + iqs62x = iqs620_pwm->iqs62x; + + mutex_lock(&iqs620_pwm->lock); + + /* + * The duty cycle generated by the device is calculated as follows: + * + * duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms + * + * ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255 + * (inclusive). Therefore the lowest duty cycle the device can generate + * while the output is enabled is 1 / 256 ms. + * + * For lower duty cycles (e.g. 0), the PWM output is simply disabled to + * allow an on-board pull-down resistor to hold the GPIO3/LTX pin low. + */ + duty_scale = state->duty_cycle * 256 / IQS620_PWM_PERIOD_NS; + + if (!state->enabled || !duty_scale) { + ret = regmap_update_bits(iqs62x->map, IQS620_PWR_SETTINGS, + IQS620_PWR_SETTINGS_PWM_OUT, 0); + if (ret) + goto err_mutex; + } + + if (duty_scale) { + ret = regmap_write(iqs62x->map, IQS620_PWM_DUTY_CYCLE, + min(duty_scale - 1, 0xFF)); + if (ret) + goto err_mutex; + } + + if (state->enabled && duty_scale) + ret = regmap_update_bits(iqs62x->map, IQS620_PWR_SETTINGS, + IQS620_PWR_SETTINGS_PWM_OUT, 0xFF); + +err_mutex: + mutex_unlock(&iqs620_pwm->lock); + + return ret; +} + +static void iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + struct iqs620_pwm_private *iqs620_pwm; + struct iqs62x_core *iqs62x; + unsigned int val; + int ret; + + iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip); + iqs62x = iqs620_pwm->iqs62x; + + mutex_lock(&iqs620_pwm->lock); + + /* + * Since the device cannot generate a 0% duty cycle, requests to do so + * cause subsequent calls to iqs620_pwm_get_state to report the output + * as disabled with duty cycle equal to that which was in use prior to + * the request. This is not ideal, but is the best compromise based on + * the capabilities of the device. + */ + ret = regmap_read(iqs62x->map, IQS620_PWR_SETTINGS, &val); + if (ret) + goto err_mutex; + state->enabled = val & IQS620_PWR_SETTINGS_PWM_OUT; + + ret = regmap_read(iqs62x->map, IQS620_PWM_DUTY_CYCLE, &val); + if (ret) + goto err_mutex; + state->duty_cycle = DIV_ROUND_UP((val + 1) * IQS620_PWM_PERIOD_NS, 256); + state->period = IQS620_PWM_PERIOD_NS; + +err_mutex: + mutex_unlock(&iqs620_pwm->lock); + + if (ret) + dev_err(iqs620_pwm->chip.dev, "Failed to get state: %d\n", ret); +} + +static int iqs620_pwm_notifier(struct notifier_block *notifier, + unsigned long event_flags, void *context) +{ + struct iqs620_pwm_private *iqs620_pwm; + int ret; + + iqs620_pwm = container_of(notifier, struct iqs620_pwm_private, + notifier); + + if (!completion_done(&iqs620_pwm->chip_ready) || + !(event_flags & BIT(IQS62X_EVENT_SYS_RESET))) + return NOTIFY_DONE; + + ret = iqs620_pwm_apply(&iqs620_pwm->chip, &iqs620_pwm->chip.pwms[0], + &iqs620_pwm->chip.pwms[0].state); + if (ret) { + dev_err(iqs620_pwm->chip.dev, + "Failed to re-initialize device: %d\n", ret); + return NOTIFY_BAD; + } + + return NOTIFY_OK; +} + +static const struct pwm_ops iqs620_pwm_ops = { + .apply = iqs620_pwm_apply, + .get_state = iqs620_pwm_get_state, + .owner = THIS_MODULE, +}; + +static void iqs620_pwm_notifier_unregister(void *context) +{ + struct iqs620_pwm_private *iqs620_pwm = context; + int ret; + + ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh, + &iqs620_pwm->notifier); + if (ret) + dev_err(iqs620_pwm->chip.dev, + "Failed to unregister notifier: %d\n", ret); +} + +static int iqs620_pwm_probe(struct platform_device *pdev) +{ + struct iqs620_pwm_private *iqs620_pwm; + int ret; + + iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL); + if (!iqs620_pwm) + return -ENOMEM; + + platform_set_drvdata(pdev, iqs620_pwm); + iqs620_pwm->iqs62x = dev_get_drvdata(pdev->dev.parent); + + iqs620_pwm->chip.dev = &pdev->dev; + iqs620_pwm->chip.ops = &iqs620_pwm_ops; + iqs620_pwm->chip.base = -1; + iqs620_pwm->chip.npwm = 1; + + init_completion(&iqs620_pwm->chip_ready); + mutex_init(&iqs620_pwm->lock); + + iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier; + ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh, + &iqs620_pwm->notifier); + if (ret) { + dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret); + return ret; + } + + ret = devm_add_action_or_reset(&pdev->dev, + iqs620_pwm_notifier_unregister, + iqs620_pwm); + if (ret) + return ret; + + ret = pwmchip_add(&iqs620_pwm->chip); + if (ret) { + dev_err(&pdev->dev, "Failed to add device: %d\n", ret); + return ret; + } + + /* + * pwmchip_add is called last to avoid a messy tear-down path, so the + * following completion prevents iqs620_pwm_notifier from referencing + * the pwm_chip structure until it has been completely initialized. + */ + complete_all(&iqs620_pwm->chip_ready); + + return 0; +} + +static int iqs620_pwm_remove(struct platform_device *pdev) +{ + struct iqs620_pwm_private *iqs620_pwm = platform_get_drvdata(pdev); + int ret; + + ret = pwmchip_remove(&iqs620_pwm->chip); + if (ret) + dev_err(&pdev->dev, "Failed to remove device: %d\n", ret); + + return ret; +} + +static struct platform_driver iqs620_pwm_platform_driver = { + .driver = { + .name = IQS620_DRV_NAME_PWM, + }, + .probe = iqs620_pwm_probe, + .remove = iqs620_pwm_remove, +}; +module_platform_driver(iqs620_pwm_platform_driver); + +MODULE_AUTHOR("Jeff LaBundy "); +MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:" IQS620_DRV_NAME_PWM);