[PATCH v3 4/4] i2c: Add multi-instantiate pseudo driver

Hans de Goede
2018-08-07T08:05:39Z

On systems with ACPI instantiated i2c-clients, normally there is 1 fw_node
per i2c-device and that fw-node contains 1 I2cSerialBus resource for that 1
i2c-device.

But in some rare cases the manufacturer has decided to describe multiple
i2c-devices in a single ACPI fwnode with multiple I2cSerialBus resources.

An earlier attempt to fix this in the i2c-core resulted in a lot of extra
code to support this corner-case.

This commit introduces a new i2c-multi-instantiate driver which fixes this
in a different way. This new driver can be built as a module which will
only loaded on affected systems.

This driver will instantiate a new i2c-client per I2cSerialBus resource,
using the driver_data from the acpi_device_id it is binding to to tell it
which chip-type (and optional irq-resource) to use when instantiating.

Note this driver depends on a platform device being instantiated for the
ACPI fwnode, see the i2c_multi_instantiate_ids list of ACPI device-ids in
drivers/acpi/scan.c: acpi_device_enumeration_by_parent().

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
MAINTAINERS | 6 +
drivers/platform/x86/Kconfig | 11 ++
drivers/platform/x86/Makefile | 1 +
drivers/platform/x86/i2c-multi-instantiate.c | 131 +++++++++++++++++++
4 files changed, 149 insertions(+)
create mode 100644 drivers/platform/x86/i2c-multi-instantiate.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 9b377508f24f..09e16d76cab7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6657,6 +6657,12 @@ F: drivers/i2c/i2c-mux.c
F: drivers/i2c/muxes/
F: include/linux/i2c-mux.h

+I2C MULTI INSTANTIATE DRIVER
+M: Hans de Goede <hdegoede@redhat.com>
+L: linux-i2c@vger.kernel.org
+S: Maintained
+F: drivers/drivers/platform/x86/i2c-multi-instantiate.c
+
I2C MV64XXX MARVELL AND ALLWINNER DRIVER
M: Gregory CLEMENT <gregory.clement@bootlin.com>
L: linux-i2c@vger.kernel.org
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 85a93453237c..8256629f58f7 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -1219,6 +1219,17 @@ config INTEL_CHTDC_TI_PWRBTN
To compile this driver as a module, choose M here: the module
will be called intel_chtdc_ti_pwrbtn.

+config I2C_MULTI_INSTANTIATE
+ tristate "I2C multi instantiate pseudo device driver"
+ depends on I2C && ACPI
+ help
+ Some ACPI bases systems list multiple i2c-devices in a single ACPI
+ firmware-node. This driver will instantiate separate i2c-clients
+ for each device in the firmware-node.
+
+ To compile this driver as a module, choose M here: the module
+ will be called i2c-multi-instantiate.
+
endif # X86_PLATFORM_DEVICES

config PMC_ATOM
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 8d9477114fb5..e6d1becf81ce 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -91,3 +91,4 @@ obj-$(CONFIG_PMC_ATOM) += pmc_atom.o
obj-$(CONFIG_MLX_PLATFORM) += mlx-platform.o
obj-$(CONFIG_INTEL_TURBO_MAX_3) += intel_turbo_max_3.o
obj-$(CONFIG_INTEL_CHTDC_TI_PWRBTN) += intel_chtdc_ti_pwrbtn.o
+obj-$(CONFIG_I2C_MULTI_INSTANTIATE) += i2c-multi-instantiate.o
diff --git a/drivers/platform/x86/i2c-multi-instantiate.c b/drivers/platform/x86/i2c-multi-instantiate.c
new file mode 100644
index 000000000000..4db4b8cabfc9
--- /dev/null
+++ b/drivers/platform/x86/i2c-multi-instantiate.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * I2C multi-instantiate driver, pseudo driver to instantiate multiple
+ * i2c-clients from a single fwnode.
+ *
+ * Copyright 2018 Hans de Goede <hdegoede@redhat.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+struct i2c_inst_data {
+ const char *type;
+ int irq_idx;
+};
+
+struct i2c_multi_inst_data {
+ int no_clients;
+ struct i2c_client *clients[0];
+};
+
+static int i2c_multi_inst_probe(struct platform_device *pdev)
+{
+ struct i2c_multi_inst_data *multi;
+ const struct acpi_device_id *match;
+ const struct i2c_inst_data *inst_data;
+ struct i2c_board_info board_info = {};
+ struct device *dev = &pdev->dev;
+ struct acpi_device *adev;
+ char name[32];
+ int i, ret;
+
+ match = acpi_match_device(dev->driver->acpi_match_table, dev);
+ if (!match) {
+ dev_err(dev, "Error ACPI match data is missing\n");
+ return -ENODEV;
+ }
+ inst_data = (const struct i2c_inst_data *)match->driver_data;
+
+ adev = ACPI_COMPANION(dev);
+
+ /* Count number of clients to instantiate */
+ for (i = 0; inst_data[i].type; i++) {}
+
+ multi = devm_kmalloc(dev,
+ offsetof(struct i2c_multi_inst_data, clients[i]),
+ GFP_KERNEL);
+ if (!multi)
+ return -ENOMEM;
+
+ multi->no_clients = i;
+
+ for (i = 0; i < multi->no_clients; i++) {
+ memset(&board_info, 0, sizeof(board_info));
+ strlcpy(board_info.type, inst_data[i].type, I2C_NAME_SIZE);
+ snprintf(name, sizeof(name), "%s-%s", match->id,
+ inst_data[i].type);
+ board_info.dev_name = name;
+ board_info.irq = 0;
+ if (inst_data[i].irq_idx != -1) {
+ ret = acpi_dev_gpio_irq_get(adev, inst_data[i].irq_idx);
+ if (ret < 0) {
+ dev_err(dev, "Error requesting irq at index %d: %d\n",
+ inst_data[i].irq_idx, ret);
+ goto error;
+ }
+ board_info.irq = ret;
+ }
+ multi->clients[i] = i2c_acpi_new_device(dev, i, &board_info);
+ if (!multi->clients[i]) {
+ dev_err(dev, "Error creating i2c-client, idx %d\n", i);
+ ret = -ENODEV;
+ goto error;
+ }
+ }
+
+ platform_set_drvdata(pdev, multi);
+ return 0;
+
+error:
+ while (--i >= 0)
+ i2c_unregister_device(multi->clients[i]);
+
+ return ret;
+}
+
+static int i2c_multi_inst_remove(struct platform_device *pdev)
+{
+ struct i2c_multi_inst_data *multi = platform_get_drvdata(pdev);
+ int i;
+
+ for (i = 0; i < multi->no_clients; i++)
+ i2c_unregister_device(multi->clients[i]);
+
+ return 0;
+}
+
+static const struct i2c_inst_data bsg1160_data[] = {
+ { "bmc150_accel", 0 },
+ { "bmc150_magn", -1 },
+ { "bmg160", -1 },
+ {}
+};
+
+/*
+ * Note new device-ids must also be added to i2c_multi_instantiate_ids in
+ * drivers/acpi/scan.c: acpi_device_enumeration_by_parent().
+ */
+static const struct acpi_device_id i2c_multi_inst_acpi_ids[] = {
+ { "BSG1160", (unsigned long)bsg1160_data },
+ { }
+};
+MODULE_DEVICE_TABLE(acpi, i2c_multi_inst_acpi_ids);
+
+static struct platform_driver i2c_multi_inst_driver = {
+ .driver = {
+ .name = "I2C multi instantiate pseudo device driver",
+ .acpi_match_table = ACPI_PTR(i2c_multi_inst_acpi_ids),
+ },
+ .probe = i2c_multi_inst_probe,
+ .remove = i2c_multi_inst_remove,
+};
+module_platform_driver(i2c_multi_inst_driver);
+
+MODULE_DESCRIPTION("I2C multi instantiate pseudo device driver");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_LICENSE("GPL");
--
2.18.0