From patchwork Tue Nov 28 08:42:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chen-Yu Tsai X-Patchwork-Id: 13470671 Received: from mail-pg1-f180.google.com (mail-pg1-f180.google.com [209.85.215.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A9D819464 for ; Tue, 28 Nov 2023 08:45:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="cM45ce9T" Received: by mail-pg1-f180.google.com with SMTP id 41be03b00d2f7-5c18a3387f5so3162458a12.1 for ; Tue, 28 Nov 2023 00:45:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1701161116; x=1701765916; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=W8/TdtPK7mZHmPEMzqlWjR5HwzhRhEqW5dnoF8OBNcQ=; b=cM45ce9T0aPOVYL8cHLw13SNbJOjmXft7RMF19iZ/cbg+uSq6R0HewkGuRu9Bi/Ea3 zBmJ3IlYx/csQOFkve9uUBhYDiFm7OMt8tHSPGfxhwpRzQghzhJOlqfKK6TTbj6hVs1I QObbpadcsQEryUf8nyPZjTNLLeLpwUfoHAgj4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701161116; x=1701765916; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=W8/TdtPK7mZHmPEMzqlWjR5HwzhRhEqW5dnoF8OBNcQ=; b=WwyUPBsXQnKR94U4LgaGaFVPAgD41//1B7JL/O2sK0l5274mEUC/9jxwxh+a9n28Jb 1P4PGxmCKJ3ZDdWePp6D52XSfFBNfrGd1hjESOF9nMpRRGE8r/X8WjcnTRNwIWpj3JXz ed6pev8ZLm1TXaqMgJAygCUvvmDgB/9uZ6yYUS2earLks+DaYCCdBF+P1rvXAJjZJGcX JBDT2N4j2nlRCpmHqKZW2gr1eBTPSCbPXSgBY329OT1TQKP5JhJ3wn/gyk+i+y6szALB Aix9h/bHeUUIOWg+Y6oPgKuU7nLvbOmoa7c1ixApJ9RsUzWxAecLVu9sm3mmycURPPDO YjNA== X-Gm-Message-State: AOJu0Yyd3Lunvh4Hg7LSaVv7Cuuf5T4ulhuQGaTa9cOKkW7NCgSmJ7zV j0lP1st603ayacds7azQ1wrf7A== X-Google-Smtp-Source: AGHT+IG6UzF6jCgkNYomISFp5LxHRmJmbSt0cMuJU32MtFDCyOlf9c7ui7iv5r+wF6dwufogT4B1GQ== X-Received: by 2002:a05:6a20:d48d:b0:189:dc00:cf85 with SMTP id im13-20020a056a20d48d00b00189dc00cf85mr14610135pzb.36.1701161116308; Tue, 28 Nov 2023 00:45:16 -0800 (PST) Received: from wenstp920.tpe.corp.google.com ([2401:fa00:1:10:a990:1e95:a915:9c70]) by smtp.gmail.com with ESMTPSA id j1-20020a170902c08100b001ab39cd875csm8358074pld.133.2023.11.28.00.45.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Nov 2023 00:45:15 -0800 (PST) From: Chen-Yu Tsai To: Rob Herring , Frank Rowand , Krzysztof Kozlowski , Conor Dooley , Matthias Brugger , AngeloGioacchino Del Regno , Wolfram Sang , Benson Leung , Tzung-Bi Shih Cc: Chen-Yu Tsai , chrome-platform@lists.linux.dev, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, Douglas Anderson , Johan Hovold , Hsin-Yi Wang , Dmitry Torokhov , andriy.shevchenko@linux.intel.com, Jiri Kosina , linus.walleij@linaro.org, broonie@kernel.org, gregkh@linuxfoundation.org, hdegoede@redhat.com, james.clark@arm.com, james@equiv.tech, keescook@chromium.org, rafael@kernel.org, tglx@linutronix.de, Jeff LaBundy , linux-input@vger.kernel.org, linux-i2c@vger.kernel.org Subject: [RFC PATCH v3 3/5] platform/chrome: Introduce device tree hardware prober Date: Tue, 28 Nov 2023 16:42:32 +0800 Message-ID: <20231128084236.157152-4-wenst@chromium.org> X-Mailer: git-send-email 2.43.0.rc1.413.gea7ed67945-goog In-Reply-To: <20231128084236.157152-1-wenst@chromium.org> References: <20231128084236.157152-1-wenst@chromium.org> Precedence: bulk X-Mailing-List: chrome-platform@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Some devices are designed and manufactured with some components having multiple drop-in replacement options. These components are often connected to the mainboard via ribbon cables, having the same signals and pin assignments across all options. These may include the display panel and touchscreen on laptops and tablets, and the trackpad on laptops. Sometimes which component option is used in a particular device can be detected by some firmware provided identifier, other times that information is not available, and the kernel has to try to probe each device. This change attempts to make the "probe each device" case cleaner. The current approach is to have all options added and enabled in the device tree. The kernel would then bind each device and run each driver's probe function. This works, but has been broken before due to the introduction of asynchronous probing, causing multiple instances requesting "shared" resources, such as pinmuxes, GPIO pins, interrupt lines, at the same time, with only one instance succeeding. Work arounds for these include moving the pinmux to the parent I2C controller, using GPIO hogs or pinmux settings to keep the GPIO pins in some fixed configuration, and requesting the interrupt line very late. Such configurations can be seen on the MT8183 Krane Chromebook tablets, and the Qualcomm sc8280xp-based Lenovo Thinkpad 13S. Instead of this delicate dance between drivers and device tree quirks, this change introduces a simple I2C component prober. For any given class of devices on the same I2C bus, it will go through all of them, doing a simple I2C read transfer and see which one of them responds. It will then enable the device that responds. This requires some minor modifications in the existing device tree. The status for all the device nodes for the component options must be set to "failed-needs-probe". This makes it clear that some mechanism is needed to enable one of them, and also prevents the prober and device drivers running at the same time. Signed-off-by: Chen-Yu Tsai --- Changes since v2: - Addressed Rob's comments - Move remaining driver code to drivers/platform/chrome/ - Depend on rather than select CONFIG_I2C - Copy machine check to driver init function - Addressed Andy's comments - Explicitly mention "device tree" or OF in driver name, description and Kconfig symbol - Drop filename from inside the file - Switch to passing "struct device *" to shorten lines - Move "ret = 0" to just before for_each_child_of_node(i2c_node, node) - Make loop variable size_t (instead of unsigned int as Andy asked) - Use PLATFORM_DEVID_NONE instead of raw -1 - Use standard goto error path pattern in hw_prober_driver_init() - Changes since v1: - New patch --- drivers/platform/chrome/Kconfig | 11 +++ drivers/platform/chrome/Makefile | 1 + .../platform/chrome/chromeos_of_hw_prober.c | 89 +++++++++++++++++++ 3 files changed, 101 insertions(+) create mode 100644 drivers/platform/chrome/chromeos_of_hw_prober.c diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig index 7a83346bfa53..aa161f2f09e3 100644 --- a/drivers/platform/chrome/Kconfig +++ b/drivers/platform/chrome/Kconfig @@ -61,6 +61,17 @@ config CHROMEOS_TBMC To compile this driver as a module, choose M here: the module will be called chromeos_tbmc. +config CHROMEOS_OF_HW_PROBER + bool "ChromeOS Device Tree Hardware Prober" + depends on OF + depends on I2C + select OF_DYNAMIC + default OF + help + This option enables the device tree hardware prober for ChromeOS + devices. The driver will probe the correct component variant in + devices that have multiple drop-in options for one component. + config CROS_EC tristate "ChromeOS Embedded Controller" select CROS_EC_PROTO diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile index 2dcc6ccc2302..21a9d5047053 100644 --- a/drivers/platform/chrome/Makefile +++ b/drivers/platform/chrome/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_CHROMEOS_ACPI) += chromeos_acpi.o obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o obj-$(CONFIG_CHROMEOS_PRIVACY_SCREEN) += chromeos_privacy_screen.o obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o +obj-$(CONFIG_CHROMEOS_OF_HW_PROBER) += chromeos_of_hw_prober.o obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o obj-$(CONFIG_CROS_EC) += cros_ec.o obj-$(CONFIG_CROS_EC_I2C) += cros_ec_i2c.o diff --git a/drivers/platform/chrome/chromeos_of_hw_prober.c b/drivers/platform/chrome/chromeos_of_hw_prober.c new file mode 100644 index 000000000000..13aaad6382aa --- /dev/null +++ b/drivers/platform/chrome/chromeos_of_hw_prober.c @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ChromeOS Device Tree Hardware Prober + * + * Copyright (c) 2023 Google LLC + */ + +#include +#include +#include +#include + +#define DRV_NAME "chromeos_of_hw_prober" + +/** + * struct hw_prober_entry - Holds an entry for the hardware prober + * + * @compatible: compatible string to match against the machine + * @prober: prober function to call when machine matches + * @data: extra data for the prober function + */ +struct hw_prober_entry { + const char *compatible; + int (*prober)(struct device *dev, const void *data); + const void *data; +}; + +static int chromeos_i2c_component_prober(struct device *dev, const void *data) +{ + const char *type = data; + + return i2c_of_probe_component(dev, type); +} + +static const struct hw_prober_entry hw_prober_platforms[] = { + { .compatible = "google,hana", .prober = chromeos_i2c_component_prober, .data = "touchscreen" }, + { .compatible = "google,hana", .prober = chromeos_i2c_component_prober, .data = "trackpad" }, +}; + +static int chromeos_of_hw_prober_probe(struct platform_device *pdev) +{ + for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) + if (of_machine_is_compatible(hw_prober_platforms[i].compatible)) { + int ret; + + ret = hw_prober_platforms[i].prober(&pdev->dev, + hw_prober_platforms[i].data); + if (ret) + return ret; + } + + return 0; +} + +static struct platform_driver chromeos_of_hw_prober_driver = { + .probe = chromeos_of_hw_prober_probe, + .driver = { + .name = DRV_NAME, + }, +}; + +static int __init chromeos_of_hw_prober_driver_init(void) +{ + struct platform_device *pdev; + size_t i; + int ret; + + for (i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) + if (of_machine_is_compatible(hw_prober_platforms[i].compatible)) + break; + if (i == ARRAY_SIZE(hw_prober_platforms)) + return 0; + + ret = platform_driver_register(&chromeos_of_hw_prober_driver); + if (ret) + return ret; + + pdev = platform_device_register_simple(DRV_NAME, PLATFORM_DEVID_NONE, NULL, 0); + if (IS_ERR(pdev)) + goto err; + + return 0; + +err: + platform_driver_unregister(&chromeos_of_hw_prober_driver); + + return PTR_ERR(pdev); +} +device_initcall(chromeos_of_hw_prober_driver_init);