From patchwork Sat Jan 6 16:09:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans de Goede X-Patchwork-Id: 760731 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 144D479C3 for ; Sat, 6 Jan 2024 16:09:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KTMnP8cx" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1704557398; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JzpM8XnbTJAfg15a2BeUriVVEF0AwqH58tuAhGJLep4=; b=KTMnP8cxW4AOtbJ0B8NfwzjuGzEqC157i8kK55JNtDPjyFiF26wmhVotRcCbVIiWqZV3fA asP2cbBzbpl45JktInBiVetkhJ5j6res9SmpoSCGsT/+kpKHgZ6v51L7BPOoRKk9OOQDLp pkAZyByjAfjyhVqH/Cc6zEGW43oRSMg= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-131-evxJyZRdM_mNPEcC49dcvg-1; Sat, 06 Jan 2024 11:09:53 -0500 X-MC-Unique: evxJyZRdM_mNPEcC49dcvg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1FF1438143AE; Sat, 6 Jan 2024 16:09:53 +0000 (UTC) Received: from localhost.localdomain (unknown [10.39.192.13]) by smtp.corp.redhat.com (Postfix) with ESMTP id 65A793C27; Sat, 6 Jan 2024 16:09:51 +0000 (UTC) From: Hans de Goede To: =?utf-8?q?Pali_Roh=C3=A1r?= , =?utf-8?q?Ilpo_J=C3=A4rvi?= =?utf-8?q?nen?= , Andy Shevchenko , Paul Menzel , Jean Delvare , Andi Shyti Cc: Hans de Goede , eric.piel@tremplin-utc.net, Marius Hoch , Dell.Client.Kernel@dell.com, Kai Heng Feng , platform-driver-x86@vger.kernel.org, Wolfram Sang , linux-i2c@vger.kernel.org Subject: [PATCH v2 5/6] platform/x86: dell-smo8800: Add support for probing for the accelerometer i2c address Date: Sat, 6 Jan 2024 17:09:32 +0100 Message-ID: <20240106160935.45487-6-hdegoede@redhat.com> In-Reply-To: <20240106160935.45487-1-hdegoede@redhat.com> References: <20240106160935.45487-1-hdegoede@redhat.com> Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Unfortunately the SMOxxxx ACPI device does not contain the i2c-address of the accelerometer. So a DMI product-name to address mapping table is used. At support to have the kernel probe for the i2c-address for modesl which are not on the list. The new probing code sits behind a new probe_i2c_addr module parameter, which is disabled by default because probing might be dangerous. Signed-off-by: Hans de Goede --- drivers/platform/x86/dell/dell-smo8800.c | 112 +++++++++++++++++++++-- 1 file changed, 105 insertions(+), 7 deletions(-) diff --git a/drivers/platform/x86/dell/dell-smo8800.c b/drivers/platform/x86/dell/dell-smo8800.c index 58bb7275ba5c..021ad31eb84d 100644 --- a/drivers/platform/x86/dell/dell-smo8800.c +++ b/drivers/platform/x86/dell/dell-smo8800.c @@ -29,6 +29,10 @@ static bool use_iio_driver; module_param(use_iio_driver, bool, 0444); MODULE_PARM_DESC(use_iio_driver, "Use IIO accelerometer driver instead of /dev/freefall chardev + evdev joystick emulation"); +static bool probe_i2c_addr; +module_param(probe_i2c_addr, bool, 0444); +MODULE_PARM_DESC(probe_i2c_addr, "Probe the i801 I2C bus for the accelerometer on models where the address is unknown"); + struct smo8800_device { u32 irq; /* acpi device irq */ atomic_t counter; /* count after last read */ @@ -150,6 +154,82 @@ static int smo8800_find_i801(struct device *dev, void *data) return 1; } +/* + * This is the kernel version of the single register device sanity checks from + * the i2c_safety_check function from lm_sensors sensor-detect script: + * This is meant to prevent access to 1-register-only devices, + * which are designed to be accessed with SMBus receive byte and SMBus send + * byte transactions (i.e. short reads and short writes) and treat SMBus + * read byte as a real write followed by a read. The device detection + * routines would write random values to the chip with possibly very nasty + * results for the hardware. Note that this function won't catch all such + * chips, as it assumes that reads and writes relate to the same register, + * but that's the best we can do. + */ +static int i2c_safety_check(struct smo8800_device *smo8800, struct i2c_adapter *adap, u8 addr) +{ + union i2c_smbus_data smbus_data; + int err; + u8 data; + + /* + * First receive a byte from the chip, and remember it. This + * also checks if there is a device at the address at all. + */ + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE, &smbus_data); + if (err < 0) + return err; + + data = smbus_data.byte; + + /* + * Receive a byte again; very likely to be the same for + * 1-register-only devices. + */ + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE, &smbus_data); + if (err < 0) + return err; + + if (smbus_data.byte != data) + return 0; /* Not a 1-register-only device. */ + + /* + * Then try a standard byte read, with a register offset equal to + * the read byte; for 1-register-only device this should read + * the same byte value in return. + */ + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, data, + I2C_SMBUS_BYTE_DATA, &smbus_data); + if (err < 0) + return err; + + if (smbus_data.byte != data) + return 0; /* Not a 1-register-only device. */ + + /* + * Then try a standard byte read, with a slightly different register + * offset; this should again read the register offset in return. + */ + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, data ^ 0x01, + I2C_SMBUS_BYTE_DATA, &smbus_data); + if (err < 0) + return err; + + if (smbus_data.byte != (data ^ 0x01)) + return 0; /* Not a 1-register-only device. */ + + /* + * Apparently this is a 1-register-only device, restore the original + * register value and leave it alone. + */ + i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, data, + I2C_SMBUS_BYTE, NULL); + dev_warn(smo8800->dev, "I2C safety check for address 0x%02x failed, skipping\n", addr); + return -ENODEV; +} + /* * Set label to let iio-sensor-proxy know these freefall sensors are located in * the laptop base (not the display) and are not intended for screen rotation. @@ -165,12 +245,19 @@ const struct software_node smo8800_accel_node = { static int smo8800_detect_accel(struct smo8800_device *smo8800, struct i2c_adapter *adap, u8 addr, - struct i2c_board_info *info) + struct i2c_board_info *info, bool probe) { union i2c_smbus_data smbus_data; const char *type; int err; + if (probe) { + dev_info(smo8800->dev, "Probing for accelerometer on address 0x%02x\n", addr); + err = i2c_safety_check(smo8800, adap, addr); + if (err < 0) + return err; + } + err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, LIS3_WHO_AM_I, I2C_SMBUS_BYTE_DATA, &smbus_data); if (err < 0) { @@ -256,17 +343,25 @@ static void smo8800_instantiate_i2c_client(struct smo8800_device *smo8800) } } - if (!addr) { + if (addr) { + /* Always detect the accel-type, this also checks the accel is actually there */ + err = smo8800_detect_accel(smo8800, adap, addr, &info, false); + if (err) + goto put_adapter; + } else if (probe_i2c_addr) { + /* First try address 0x29 (most used) and then try 0x1d */ + if (smo8800_detect_accel(smo8800, adap, 0x29, &info, true) != 0 && + smo8800_detect_accel(smo8800, adap, 0x1d, &info, true) != 0) { + dev_warn(smo8800->dev, "No accelerometer found\n"); + goto put_adapter; + } + } else { dev_warn(smo8800->dev, "Accelerometer lis3lv02d is present on SMBus but its address is unknown, skipping registration\n"); + dev_info(smo8800->dev, "Pass dell_smo8800.probe_i2c_addr=1 on the kernel commandline to probe, this may be dangerous!\n"); goto put_adapter; } - /* Always detect the accel-type, this also checks the accel is actually there */ - err = smo8800_detect_accel(smo8800, adap, addr, &info); - if (err) - goto put_adapter; - /* * Unless using the IIO driver is requested, override the detected type * with "lis3lv02d" so that drivers/misc/lis3lv02d/lis3lv02d.c is used @@ -285,6 +380,9 @@ static void smo8800_instantiate_i2c_client(struct smo8800_device *smo8800) } else { dev_info(smo8800->dev, "Registered %s accelerometer on address 0x%02x\n", info.type, info.addr); + if (!addr) + dev_info(smo8800->dev, + "Please report this address upstream together with the output of 'cat /sys/class/dmi/id/product_name'\n"); } put_adapter: i2c_put_adapter(adap);