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During an actual submission this'll be broken up into two commits, but I'd like to get some feedback on whether this is the correct path for me to be going down. Background: Microchip has a family of chips - the VSC7511, 7512, 7513, and 7514. The last two have an internal MIPS processor, which are supported by drivers/net/ethernet/mscc/ocelot_*. The former two lack this processor. All four chips can be configured externally via a number of interfaces: SPI, I2C, PCIe... This is currently not supported and is my end goal. The networking portion of these chips have been reused in other products as well. These utilize the common code by way of mscc_ocelot_switch_lib and net/dsa/ocelot/*. Specifically the "Felix" driver. Current status: I've put out a few RFCs on the "ocelot_spi" driver. It utilizes Felix and invokes much of the network portion of the hardware (VSC7512). It works great! Thanks community :) There's more hardware that needs to get configured, however. Currently that includes general pin configuration, and an optional serial GPIO expander. The former is supported by drivers/pinctrl/pinctrl-ocelot.c and the latter by drivers/pinctrl/pinctrl-microchip-sgpio.c. These drivers have been updated to use regmap instead of iomem, but that isn't the complete story. There are two options I know about, and maybe others I don't. Option 1 - directly hook into the driver: This was the path that was done in commit b99658452355 ("net: dsa: ocelot: felix: utilize shared mscc-miim driver for indirect MDIO access"). This is in the net-next tree. In this case the Seville driver passes in its regmap to the mscc_miim_setup function, which bypasses mscc_miim_probe but allows the same driver to be used. This was my initial implementation to hook into pinctrl-ocelot and pinctrl-microchip-sgpio. The good thing about this implementation is I have direct control over the order of things happening. For instance, pinctrl might need to be configured before the MDIO bus gets probed. The bad thing about this implementation is... it doesn't work yet. My memory is fuzzy on this, but I recall noticing that the application of a devicetree pinctrl function happens in the driver probe. I ventured down this path of walking the devicetree, applying pincfg, etc. That was a path to darkness that I have abandoned. What is functioning is I have debugfs / sysfs control, so I do have the ability to do some runtime testing and verification. Option 2 - MFD (this "patch") It really seems like anything in drivers/net/dsa/ should avoid drivers/pinctl, and that MFD is the answer. This adds some complexity to pinctrl-ocelot, and I'm not sure whether that breaks the concept of MFD. So it seems like I'm either doing something unique, or I'm doing something wrong. I err on the assumption that I'm doing something wrong. pinctrl-ocelot gets its resources the device tree by way of platform_get_and_ioremap_resource. This driver has been updated to support regmap in the pinctrl tree: commit 076d9e71bcf8 ("pinctrl: ocelot: convert pinctrl to regmap") The problem comes about when this driver is probed by way of "mfd_add_devices". In an ideal world it seems like this would be handled by resources. MFD adds resources to the device before it gets probed. The probe happens and the driver is happy because platform_get_resource succeeds. In this scenario the device gets probed, but needs to know how to get its regmap... not its resource. In the "I'm running from an internal chip" scenario, the existing process of "devm_regmap_init_mmio" will suffice. But in the "I'm running from an externally controlled setup via {SPI,I2C,PCIe}" the process needs to be "get me this regmap from my parent". It seems like dev_get_regmap is a perfect candidate for this. Perhaps there is something I'm missing in the concept of resources / regmaps. But it seems like pinctrl-ocelot needs to know whether it is in an MFD scenario, and that concept didn't exist. Hence the addition of device_is_mfd as part of this patch. Since "device_is_mfd" didn't exist, it feels like I might be breaking the concept of MFD. I think this would lend itself to a pretty elegant architecture for the VSC751X externally controlled chips. In a manner similar to drivers/mfd/madera* there would be small drivers handling the prococol layers for SPI, I2C... A core driver would handle the register mappings, and could be gotten by dev_get_regmap. Every sub-device (DSA, pinctrl, other pinctrl, other things I haven't considered yet) could either rely on dev->parent directly, or in this case adjust. I can't imagine a scenario where someone would want pinctrl for the VSC7512 without the DSA side of things... but that would be possible in this architecture that would otherwise not. Signed-off-by: Colin Foster --- drivers/mfd/mfd-core.c | 6 ++++++ drivers/pinctrl/pinctrl-ocelot.c | 7 ++++++- include/linux/mfd/core.h | 2 ++ 3 files changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c index 684a011a6396..2ba6a692499b 100644 --- a/drivers/mfd/mfd-core.c +++ b/drivers/mfd/mfd-core.c @@ -33,6 +33,12 @@ static struct device_type mfd_dev_type = { .name = "mfd_device", }; +int device_is_mfd(struct platform_device *pdev) +{ + return (!strcmp(pdev->dev.type->name, mfd_dev_type.name)); +} +EXPORT_SYMBOL(device_is_mfd); + int mfd_cell_enable(struct platform_device *pdev) { const struct mfd_cell *cell = mfd_get_cell(pdev); diff --git a/drivers/pinctrl/pinctrl-ocelot.c b/drivers/pinctrl/pinctrl-ocelot.c index 0a36ec8775a3..758fbc225244 100644 --- a/drivers/pinctrl/pinctrl-ocelot.c +++ b/drivers/pinctrl/pinctrl-ocelot.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -1368,7 +1369,11 @@ static int ocelot_pinctrl_probe(struct platform_device *pdev) regmap_config.max_register = OCELOT_GPIO_SD_MAP * info->stride + 15 * 4; - info->map = devm_regmap_init_mmio(dev, base, ®map_config); + if (device_is_mfd(pdev)) + info->map = dev_get_regmap(dev->parent, "GCB"); + else + info->map = devm_regmap_init_mmio(dev, base, ®map_config); + if (IS_ERR(info->map)) { dev_err(dev, "Failed to create regmap\n"); return PTR_ERR(info->map); diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h index 0bc7cba798a3..9980bcc8456d 100644 --- a/include/linux/mfd/core.h +++ b/include/linux/mfd/core.h @@ -123,6 +123,8 @@ struct mfd_cell { int num_parent_supplies; }; +int device_is_mfd(struct platform_device *pdev); + /* * Convenience functions for clients using shared cells. Refcounting * happens automatically, with the cell's enable/disable callbacks -- 2.25.1