Hi,
On 08/08/2018 11:08 AM, Andy Shevchenko wrote:
On Wed, Aug 8, 2018 at 11:30 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
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().
Thanks for an update! My comments below.
+struct i2c_inst_data {
+ const char *type;
+ int irq_idx;
+};
+struct i2c_multi_inst_data {
+ int no_clients;
Name a bit confusing. What about num_clients?
no is often used as abbreviation for "number of" so this is a quite
normal naming scheme. But if you really want me to I can do a v5
renaming this to num_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;
Here I see the following:
- it's kinda unusual use of offsetof()
There are actually plenty of places doing this, this is the normal way
to get the size of a struct which ends with a variable sized array.
I would prefer to keep this as is.
, perhaps i*sizeof() + sizeof()
would be more understandable
- there is no guard against i == 0
i depends on the driver_data, defining a driver_data
where i == 0 is silly, still if this happens nothing bad
will happen, so I see no need for a check for this.
To solve both, it might be like
struct i2c_multi_inst_data {
int num_clients;
struct i2c_client *clients;
};
...
multi = devm_kmalloc(sizeof(*multi), GFP_KERNEL);
if (!multi)
return -ENOMEM;
multi->clients = devm_kcalloc(i, sizeof(*multi->clients), GFP_KERNEL);
if (ZERO_PTR_OR_NULL(multi->clients))
return -ENOMEM;
But I would like to hear your (other's) opinion(s).
Nack for this option, this just makes the code more
complicated and uses allocs instead of 1 for no good
reason IMHO.
Regards,
Hans
+
+ 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) {
= 0 sounds more robust
+ 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);
irq -> IRQ in the message.
+ 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)
It can be simple
while (i--)
+ 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),
We don't need ACPI_PTR for the driver which depends on ACPI.
In the general case we have an inconsistency with variable definition
(might be unused).
+ },
+ .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@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
--
2.18.0
