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Sun, 16 Feb 2020 23:32:48 +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 v5 4/7] pwm: Add support for Azoteq IQS620A PWM generator Date: Sun, 16 Feb 2020 17:32:08 -0600 Message-Id: <1581895931-6056-5-git-send-email-jeff@labundy.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1581895931-6056-1-git-send-email-jeff@labundy.com> References: <1581895931-6056-1-git-send-email-jeff@labundy.com> X-ClientProxiedBy: SN4PR0501CA0142.namprd05.prod.outlook.com (2603:10b6:803:2c::20) To SN6PR08MB5053.namprd08.prod.outlook.com (2603:10b6:805:78::25) MIME-Version: 1.0 Received: from localhost.localdomain (136.49.227.119) by SN4PR0501CA0142.namprd05.prod.outlook.com (2603:10b6:803:2c::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.20.2750.9 via Frontend Transport; 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X-Microsoft-Antispam-Message-Info: VCL+IN555tRKBJ/HeftLlYgJ8rcbNTynyb/Dkod/XUws+7OVJQfGh6fWydTplPgDP1qQ9u/F901S9cA3bBPwFQ007yvSP2tc1UDdnDA9LckKuPj1iG/opgXmS0nqEZExXwRgvLokgJiRI1/D3NA0Jj4ZMvlkaqKW4t+x8S6f6qRyIQ/GxWBv6qSGKMEe8KTRiNeqGV8lINTBDuOliL7JucGEWsG/Re4+oesAAtwiTuF+KSNBwg5hlFaz89xL2w+u0lqm5ADv1PVL/50ERqZTwJqJyaEgnWTOkhcu1fB/aIXkh6kKpzw7AQLmzBZ3yaj54ttIbQKX9Rc0SclbVjbUJoDTmqDuwCXO3+Zyk6CPRQRlPqy3kCgij+QBMeXnVLzLo58TKeqJ1y0Re6iG0PUqO/31h8Io98N7D8L1AGJ/EQxxlYZIQ7W/iizp8airDGbVHy96CW9d/HfmW69qWYSWo4lr1HRyomD4lQ0M+/OhuNUdlig2zTTzXJJX3tVhENwoNpMsSA2eRdEm0ZPVz50KSC8grIqraPlv2nPs87JDBZc= X-MS-Exchange-AntiSpam-MessageData: goPJlNTo2rTcNl662/H2plxnNa2fKeQbIzltVMhXqXGo1mImhTDy9pBLMWHsQ+WRhCHhkgr0OryxWyEjn3no5uoJkNShp2Dqw0tEH0NK3vJUqmiNmhktpFU5jXdxvFNv+zZwJdvCzdyBHuHh6GVQZw== X-OriginatorOrg: labundy.com X-MS-Exchange-CrossTenant-Network-Message-Id: 17d84f89-8827-417a-24bb-08d7b3388855 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Feb 2020 23:32:48.4755 (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: h4LM7FSJxnuADMYzDWH30aMVRij1xJFIMTmIbbU1IBvI6D8MrEa98K1u+TdSQ/bln/BOWQFaCXD1W3HNspe+ZQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR08MB5406 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@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 Reviewed-by: Uwe Kleine-König --- Changes in v5: - Replaced iqs62x->map with iqs62x->regmap throughout - Updated iqs620_pwm_probe to read the values of IQS620_PWR_SETTINGS_PWM_OUT and IQS620_PWM_DUTY_CYCLE so that iqs620_pwm_get_state reflects the actual state of the device following any changes made by a bootloader - Dropped #defines for platform_driver name and alias in favor of the actual string names Changes in v4: - Updated iqs620_pwm_apply and iqs620_pwm_get_state to hold the lock around only the minimum necessary code - Removed the completion protecting against early use of chip->pwms[0] from inside iqs620_pwm_notifier in favor of cached register values - Updated iqs620_pwm_get_state to use the cached register values instead of reading IQS620_PWR_SETTINGS_PWM_OUT and IQS620_PWM_DUTY_CYCLE (both equal to zero by default) - Added a comment in iqs620_pwm_notifier to note that the parent MFD driver prints an error message in the event of a device reset 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 | 270 ++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 281 insertions(+) create mode 100644 drivers/pwm/pwm-iqs620a.c -- 2.7.4 diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 30190be..5430b9e 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..674f0e2 --- /dev/null +++ b/drivers/pwm/pwm-iqs620a.c @@ -0,0 +1,270 @@ +// 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 + +#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 mutex lock; + bool out_en; + u8 duty_val; +}; + +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; + + /* + * 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 external pull-down resistor to hold the GPIO3/LTX pin low. + */ + duty_scale = state->duty_cycle * 256 / IQS620_PWM_PERIOD_NS; + + mutex_lock(&iqs620_pwm->lock); + + if (!state->enabled || !duty_scale) { + ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS, + IQS620_PWR_SETTINGS_PWM_OUT, 0); + if (ret) + goto err_mutex; + } + + if (duty_scale) { + u8 duty_val = min(duty_scale - 1, 0xFF); + + ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, + duty_val); + if (ret) + goto err_mutex; + + iqs620_pwm->duty_val = duty_val; + } + + if (state->enabled && duty_scale) { + ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS, + IQS620_PWR_SETTINGS_PWM_OUT, 0xFF); + if (ret) + goto err_mutex; + } + + iqs620_pwm->out_en = state->enabled; + +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; + + iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip); + + 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. + */ + state->enabled = iqs620_pwm->out_en; + state->duty_cycle = DIV_ROUND_UP((iqs620_pwm->duty_val + 1) * + IQS620_PWM_PERIOD_NS, 256); + + mutex_unlock(&iqs620_pwm->lock); + + state->period = IQS620_PWM_PERIOD_NS; +} + +static int iqs620_pwm_notifier(struct notifier_block *notifier, + unsigned long event_flags, void *context) +{ + struct iqs620_pwm_private *iqs620_pwm; + struct iqs62x_core *iqs62x; + int ret; + + if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET))) + return NOTIFY_DONE; + + iqs620_pwm = container_of(notifier, struct iqs620_pwm_private, + notifier); + iqs62x = iqs620_pwm->iqs62x; + + mutex_lock(&iqs620_pwm->lock); + + /* + * The parent MFD driver already prints an error message in the event + * of a device reset, so nothing else is printed here unless there is + * an additional failure. + */ + ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, + iqs620_pwm->duty_val); + if (ret) + goto err_mutex; + + ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS, + IQS620_PWR_SETTINGS_PWM_OUT, + iqs620_pwm->out_en ? 0xFF : 0); + +err_mutex: + mutex_unlock(&iqs620_pwm->lock); + + 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 iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent); + struct iqs620_pwm_private *iqs620_pwm; + unsigned int val; + 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 = iqs62x; + + ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val); + if (ret) + return ret; + iqs620_pwm->out_en = val & IQS620_PWR_SETTINGS_PWM_OUT; + + ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val); + if (ret) + return ret; + iqs620_pwm->duty_val = val; + + iqs620_pwm->chip.dev = &pdev->dev; + iqs620_pwm->chip.ops = &iqs620_pwm_ops; + iqs620_pwm->chip.base = -1; + iqs620_pwm->chip.npwm = 1; + + 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; +} + +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 = "iqs620a-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:iqs620a-pwm");