Hi Biju, On Mon, May 29, 2023 at 09:00:43AM +0000, Biju Das wrote: > > Subject: Re: [PATCH v5 01/11] i2c: Enhance i2c_new_ancillary_device API > > On Mon, May 22, 2023 at 11:18:39AM +0100, Biju Das wrote: > > > Renesas PMIC RAA215300 exposes two separate i2c devices, one for the > > > main device and another for rtc device. > > > > > > Enhance i2c_new_ancillary_device() to instantiate a real device. > > > > Doesn't it already instantiate a real device ? > > No, as per the code it instantiates dummy device[1] > [1] https://elixir.bootlin.com/linux/latest/source/drivers/i2c/i2c-core-base.c#L1156 And that function calls i2c_new_client_device(), which allocates a struct i2c_client that embeds a struct device, and registers that device with the kernel device core. How is that different, in terms of instantiating a "real device", from what this patch does ? > > > (eg: Instantiate rtc device from PMIC driver) > > > > > > Added helper function __i2c_new_dummy_device to share the code between > > > i2c_new_dummy_device and i2c_new_ancillary_device(). > > > > > > Also added helper function __i2c_new_client_device() to pass parent > > > dev parameter, so that the ancillary device can assign its parent > > > during creation. > > > > > > Suggested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> > > > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx> > > > --- > > > v4->v5: > > > * Replaced parameter dev->parent in __i2c_new_client_device() and > > > __i2c_new_dummy_device(). > > > * Improved error message in __i2c_new_dummy_device() by printing device name. > > > * Updated comment for ancillary's device parent > > > * Dropped aux_device_name check in i2c_new_ancillary_device(). > > > v3->v4: > > > * Dropped Rb tag from Geert as there are new changes. > > > * Introduced __i2c_new_dummy_device() to share the code between > > > i2c_new_dummy_device and i2c_new_ancillary_device(). > > > * Introduced __i2c_new_client_device() to pass parent dev > > > parameter, so that the ancillary device can assign its parent during > > > creation. > > > v3: > > > * New patch > > > > > > Ref: > > > > > > --- > > > drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 6 +- > > > drivers/i2c/i2c-core-base.c | 92 +++++++++++++------ > > - > > > drivers/media/i2c/adv748x/adv748x-core.c | 2 +- > > > drivers/media/i2c/adv7604.c | 3 +- > > > include/linux/i2c.h | 3 +- > > > 5 files changed, 69 insertions(+), 37 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > > > b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > > > index ddceafa7b637..86306b010a0a 100644 > > > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > > > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > > > @@ -1072,7 +1072,7 @@ static int adv7511_init_cec_regmap(struct adv7511 *adv) > > > int ret; > > > > > > adv->i2c_cec = i2c_new_ancillary_device(adv->i2c_main, "cec", > > > - ADV7511_CEC_I2C_ADDR_DEFAULT); > > > + ADV7511_CEC_I2C_ADDR_DEFAULT, NULL); > > > if (IS_ERR(adv->i2c_cec)) > > > return PTR_ERR(adv->i2c_cec); > > > > > > @@ -1261,7 +1261,7 @@ static int adv7511_probe(struct i2c_client *i2c) > > > adv7511_packet_disable(adv7511, 0xffff); > > > > > > adv7511->i2c_edid = i2c_new_ancillary_device(i2c, "edid", > > > - ADV7511_EDID_I2C_ADDR_DEFAULT); > > > + ADV7511_EDID_I2C_ADDR_DEFAULT, NULL); > > > if (IS_ERR(adv7511->i2c_edid)) { > > > ret = PTR_ERR(adv7511->i2c_edid); > > > goto uninit_regulators; > > > @@ -1271,7 +1271,7 @@ static int adv7511_probe(struct i2c_client *i2c) > > > adv7511->i2c_edid->addr << 1); > > > > > > adv7511->i2c_packet = i2c_new_ancillary_device(i2c, "packet", > > > - ADV7511_PACKET_I2C_ADDR_DEFAULT); > > > + ADV7511_PACKET_I2C_ADDR_DEFAULT, NULL); > > > if (IS_ERR(adv7511->i2c_packet)) { > > > ret = PTR_ERR(adv7511->i2c_packet); > > > goto err_i2c_unregister_edid; > > > diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c > > > index ae3af738b03f..3442aa80290f 100644 > > > --- a/drivers/i2c/i2c-core-base.cvvccc > > > +++ b/drivers/i2c/i2c-core-base.cckvlrgnulkj > > > @@ -893,24 +893,10 @@ int i2c_dev_irq_from_resources(const struct resource *resources, > > > return 0; > > > } > > > > > > -/** > > > - * i2c_new_client_device - instantiate an i2c device > > > - * @adap: the adapter managing the device > > > - * @info: describes one I2C device; bus_num is ignored > > > - * Context: can sleep > > > - * > > > - * Create an i2c device. Binding is handled through driver model > > > - * probe()/remove() methods. A driver may be bound to this device when we > > > - * return from this function, or any later moment (e.g. maybe hotplugging will > > > - * load the driver module). This call is not appropriate for use by mainboard > > > - * initialization logic, which usually runs during an arch_initcall() long > > > - * before any i2c_adapter could exist. > > > - * > > > - * This returns the new i2c client, which may be saved for later use with > > > - * i2c_unregister_device(); or an ERR_PTR to describe the error. > > > - */ > > > -struct i2c_client * > > > -i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info) > > > +static struct i2c_client * > > > +__i2c_new_client_device(struct i2c_adapter *adap, > > > + struct i2c_board_info const *info, > > > + struct device *parent) > > > { > > > struct i2c_client *client; > > > int status; > > > @@ -944,7 +930,7 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf > > > if (status) > > > goto out_err; > > > > > > - client->dev.parent = &client->adapter->dev; > > > + client->dev.parent = parent ? parent : &client->adapter->dev; > > > client->dev.bus = &i2c_bus_type; > > > client->dev.type = &i2c_client_type; > > > client->dev.of_node = of_node_get(info->of_node); > > > @@ -984,6 +970,28 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf > > > kfree(client); > > > return ERR_PTR(status); > > > } > > > + > > > +/** > > > + * i2c_new_client_device - instantiate an i2c device > > > + * @adap: the adapter managing the device > > > + * @info: describes one I2C device; bus_num is ignored > > > + * Context: can sleep > > > + * > > > + * Create an i2c device. Binding is handled through driver model > > > + * probe()/remove() methods. A driver may be bound to this device when we > > > + * return from this function, or any later moment (e.g. maybe hotplugging will > > > + * load the driver module). This call is not appropriate for use by mainboard > > > + * initialization logic, which usually runs during an arch_initcall() long > > > + * before any i2c_adapter could exist. > > > + * > > > + * This returns the new i2c client, which may be saved for later use with > > > + * i2c_unregister_device(); or an ERR_PTR to describe the error. > > > + */ > > > +struct i2c_client * > > > +i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info > > > +const *info) { > > > + return __i2c_new_client_device(adap, info, NULL); } > > > EXPORT_SYMBOL_GPL(i2c_new_client_device); > > > > > > /** > > > @@ -1054,6 +1062,26 @@ static struct i2c_driver dummy_driver = { > > > .id_table = dummy_id, > > > }; > > > > > > +static struct i2c_client *__i2c_new_dummy_device(struct i2c_adapter *adapter, > > > + u16 address, const char *name, > > > + struct device *parent) > > > +{ > > > + struct i2c_board_info info = { > > > + I2C_BOARD_INFO("dummy", address), > > > + }; > > > + > > > + if (name) { > > > + ssize_t ret = strscpy(info.type, name, sizeof(info.type)); > > > + > > > + if (ret < 0) > > > + return ERR_PTR(dev_err_probe(&adapter->dev, ret, > > > + "Invalid device name: %s\n", > > > + name)); > > > + } > > > + > > > + return __i2c_new_client_device(adapter, &info, parent); } > > > + > > > /** > > > * i2c_new_dummy_device - return a new i2c device bound to a dummy driver > > > * @adapter: the adapter managing the device > > > @@ -1074,11 +1102,7 @@ static struct i2c_driver dummy_driver = { > > > */ > > > struct i2c_client *i2c_new_dummy_device(struct i2c_adapter *adapter, > > > u16 address) { > > > - struct i2c_board_info info = { > > > - I2C_BOARD_INFO("dummy", address), > > > - }; > > > - > > > - return i2c_new_client_device(adapter, &info); > > > + return __i2c_new_dummy_device(adapter, address, NULL, NULL); > > > } > > > EXPORT_SYMBOL_GPL(i2c_new_dummy_device); > > > > > > @@ -1122,15 +1146,19 @@ EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device); > > > * @client: Handle to the primary client > > > * @name: Handle to specify which secondary address to get > > > * @default_addr: Used as a fallback if no secondary address was specified > > > + * @aux_device_name: Ancillary device name > > > * Context: can sleep > > > * > > > * I2C clients can be composed of multiple I2C slaves bound together in a single > > > * component. The I2C client driver then binds to the master I2C slave and needs > > > - * to create I2C dummy clients to communicate with all the other slaves. > > > + * to create I2C ancillary clients to communicate with all the other slaves. > > > * > > > - * This function creates and returns an I2C dummy client whose I2C address is > > > - * retrieved from the platform firmware based on the given slave name. If no > > > - * address is specified by the firmware default_addr is used. > > > + * This function creates and returns an I2C ancillary client whose I2C address > > > + * is retrieved from the platform firmware based on the given slave name. if > > > + * aux_device_name is specified by the firmware, > > > > Unless I'm missing something, aux_device_name isn't specified by the > > firmware, it's a function parameter. > > It is specified in the platform firmware(device tree firmware). What I meant, in the context of the documentation here, is that the address is retrieved from the platform firmware by the i2c_new_ancillary_device() function, not passed as a parameter, while the name is passed as a parameter. It's not relevant, for the documentation of this function, where the caller gets the name from. > > > the ancillary's device parent > > > + * will be set to the primary device. > > > > This doesn't seem to match the implementation. With this patch the > > ancillary device's parent is always the primary device. Are you sure > > this won't cause any regression ? > > There is no regression as existing users only instantiate dummy device. Sorry, I don't follow you here. Existing callers of i2c_new_ancillary_device() today get an i2c_client device whose parent is the I2C adapter. With this patch they will get an i2c_client device whose parent is the main i2c_client. That's a change in behaviour, which could cause all sorts of issues. > > And why do you need this ? > > As per Krzysztof [2], > > The DT schema allows multiple addresses for children. But we lack > implementation of parent child relationship, As parent owns the resources. > Child device needs to parse parent node to get some resource > like clocks. > > [2] https://lore.kernel.org/linux-renesas-soc/TYCPR01MB5933BFFD4EB556F5FB4EA82186729@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ The I2C ancillary clients are not meant to be handled by separate drivers. You're supposed to have one device node in DT, which causes the I2C core to instantiate a main i2c_client, and bind it to one driver. That driver then uses i2c_new_ancillary_device() to create other i2c_client instances for the secondary I2C addresses. Those i2c_client instances are not bound to a separate driver, so there should be no code that needs to look at the parent for resources. > > > If no address is specified by the firmware > > > + * default_addr is used. If no aux_device_name is specified by the > > > + firmware, it > > > > Same here regarding firmware. > > > > > + * will create an I2C dummy client. > > > * > > > * On DT-based platforms the address is retrieved from the "reg" property entry > > > * cell whose "reg-names" value matches the slave name. > > > @@ -1139,8 +1167,9 @@ EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device); > > > * i2c_unregister_device(); or an ERR_PTR to describe the error. > > > */ > > > struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client, > > > - const char *name, > > > - u16 default_addr) > > > + const char *name, > > > + u16 default_addr, > > > + const char *aux_device_name) > > > { > > > struct device_node *np = client->dev.of_node; > > > u32 addr = default_addr; > > > @@ -1153,7 +1182,8 @@ struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client, > > > } > > > > > > dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr); > > > - return i2c_new_dummy_device(client->adapter, addr); > > > + return __i2c_new_dummy_device(client->adapter, addr, aux_device_name, > > > + &client->dev); > > > } > > > EXPORT_SYMBOL_GPL(i2c_new_ancillary_device); > > > > > > diff --git a/drivers/media/i2c/adv748x/adv748x-core.c > > > b/drivers/media/i2c/adv748x/adv748x-core.c > > > index 4498d78a2357..5bdf7b0c6bf3 100644 > > > --- a/drivers/media/i2c/adv748x/adv748x-core.c > > > +++ b/drivers/media/i2c/adv748x/adv748x-core.c > > > @@ -186,7 +186,7 @@ static int adv748x_initialise_clients(struct > > adv748x_state *state) > > > state->i2c_clients[i] = i2c_new_ancillary_device( > > > state->client, > > > adv748x_default_addresses[i].name, > > > - adv748x_default_addresses[i].default_addr); > > > + adv748x_default_addresses[i].default_addr, > > NULL); > > > > > > if (IS_ERR(state->i2c_clients[i])) { > > > adv_err(state, "failed to create i2c client %u\n", i); > > diff --git > > > a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c index > > > 3d0898c4175e..63fa44c9d27c 100644 > > > --- a/drivers/media/i2c/adv7604.c > > > +++ b/drivers/media/i2c/adv7604.c > > > @@ -2935,7 +2935,8 @@ static struct i2c_client > > *adv76xx_dummy_client(struct v4l2_subdev *sd, > > > else > > > new_client = i2c_new_ancillary_device(client, > > > adv76xx_default_addresses[page].name, > > > - adv76xx_default_addresses[page].default_addr); > > > + adv76xx_default_addresses[page].default_addr, > > > + NULL); > > > > > > if (!IS_ERR(new_client)) > > > io_write(sd, io_reg, new_client->addr << 1); diff --git > > > a/include/linux/i2c.h b/include/linux/i2c.h index > > > 13a1ce38cb0c..0ce344724209 100644 > > > --- a/include/linux/i2c.h > > > +++ b/include/linux/i2c.h > > > @@ -489,7 +489,8 @@ devm_i2c_new_dummy_device(struct device *dev, > > > struct i2c_adapter *adap, u16 addr struct i2c_client * > > > i2c_new_ancillary_device(struct i2c_client *client, > > > const char *name, > > > - u16 default_addr); > > > + u16 default_addr, > > > + const char *aux_device_name); > > > > > > void i2c_unregister_device(struct i2c_client *client); > > > -- Regards, Laurent Pinchart
