diff options
| -rw-r--r-- | doc/device-tree-bindings/i2c/i2c-mux.txt | 60 | ||||
| -rw-r--r-- | drivers/i2c/Kconfig | 2 | ||||
| -rw-r--r-- | drivers/i2c/Makefile | 2 | ||||
| -rw-r--r-- | drivers/i2c/muxes/Kconfig | 8 | ||||
| -rw-r--r-- | drivers/i2c/muxes/Makefile | 6 | ||||
| -rw-r--r-- | drivers/i2c/muxes/i2c-mux-uclass.c | 198 | ||||
| -rw-r--r-- | include/dm/uclass-id.h | 1 | ||||
| -rw-r--r-- | include/i2c.h | 39 |
8 files changed, 316 insertions, 0 deletions
diff --git a/doc/device-tree-bindings/i2c/i2c-mux.txt b/doc/device-tree-bindings/i2c/i2c-mux.txt new file mode 100644 index 0000000..af84cce --- /dev/null +++ b/doc/device-tree-bindings/i2c/i2c-mux.txt @@ -0,0 +1,60 @@ +Common i2c bus multiplexer/switch properties. + +An i2c bus multiplexer/switch will have several child busses that are +numbered uniquely in a device dependent manner. The nodes for an i2c bus +multiplexer/switch will have one child node for each child +bus. + +Required properties: +- #address-cells = <1>; +- #size-cells = <0>; + +Required properties for child nodes: +- #address-cells = <1>; +- #size-cells = <0>; +- reg : The sub-bus number. + +Optional properties for child nodes: +- Other properties specific to the multiplexer/switch hardware. +- Child nodes conforming to i2c bus binding + + +Example : + + /* + An NXP pca9548 8 channel I2C multiplexer at address 0x70 + with two NXP pca8574 GPIO expanders attached, one each to + ports 3 and 4. + */ + + mux@70 { + compatible = "nxp,pca9548"; + reg = <0x70>; + #address-cells = <1>; + #size-cells = <0>; + + i2c@3 { + #address-cells = <1>; + #size-cells = <0>; + reg = <3>; + + gpio1: gpio@38 { + compatible = "nxp,pca8574"; + reg = <0x38>; + #gpio-cells = <2>; + gpio-controller; + }; + }; + i2c@4 { + #address-cells = <1>; + #size-cells = <0>; + reg = <4>; + + gpio2: gpio@38 { + compatible = "nxp,pca8574"; + reg = <0x38>; + #gpio-cells = <2>; + gpio-controller; + }; + }; + }; diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig index 86fb36b..caee3d8 100644 --- a/drivers/i2c/Kconfig +++ b/drivers/i2c/Kconfig @@ -73,3 +73,5 @@ config SYS_I2C_UNIPHIER_F help Support for UniPhier FIFO-builtin I2C controller driver. This I2C controller is used on PH1-Pro4 or newer UniPhier SoCs. + +source "drivers/i2c/muxes/Kconfig" diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile index d9e912f..dc9e81b 100644 --- a/drivers/i2c/Makefile +++ b/drivers/i2c/Makefile @@ -37,3 +37,5 @@ obj-$(CONFIG_SYS_I2C_TEGRA) += tegra_i2c.o obj-$(CONFIG_SYS_I2C_UNIPHIER) += i2c-uniphier.o obj-$(CONFIG_SYS_I2C_UNIPHIER_F) += i2c-uniphier-f.o obj-$(CONFIG_SYS_I2C_ZYNQ) += zynq_i2c.o + +obj-y += muxes/ diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig new file mode 100644 index 0000000..a05b32d --- /dev/null +++ b/drivers/i2c/muxes/Kconfig @@ -0,0 +1,8 @@ +config I2C_MUX + bool "Suport I2C multiplexers" + depends on DM_I2C + help + This enables I2C buses to be multiplexed, so that you can select + one of several buses using some sort of control mechanism. The + bus select is handled automatically when that bus is accessed, + using a suitable I2C MUX driver. diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile new file mode 100644 index 0000000..7583e3a --- /dev/null +++ b/drivers/i2c/muxes/Makefile @@ -0,0 +1,6 @@ +# +# Copyright (c) 2015 Google, Inc +# +# SPDX-License-Identifier: GPL-2.0+ +# +obj-$(CONFIG_I2C_MUX) += i2c-mux-uclass.o diff --git a/drivers/i2c/muxes/i2c-mux-uclass.c b/drivers/i2c/muxes/i2c-mux-uclass.c new file mode 100644 index 0000000..3f52bff --- /dev/null +++ b/drivers/i2c/muxes/i2c-mux-uclass.c @@ -0,0 +1,198 @@ +/* + * Copyright (c) 2015 Google, Inc + * Written by Simon Glass <sjg@chromium.org> + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <common.h> +#include <dm.h> +#include <errno.h> +#include <i2c.h> +#include <dm/lists.h> +#include <dm/root.h> + +DECLARE_GLOBAL_DATA_PTR; + +/** + * struct i2c_mux: Information the uclass stores about an I2C mux + * + * @selected: Currently selected mux, or -1 for none + * @i2c_bus: I2C bus to use for communcation + */ +struct i2c_mux { + int selected; + struct udevice *i2c_bus; +}; + +/** + * struct i2c_mux_bus: Information about each bus the mux controls + * + * @channel: Channel number used to select this bus + */ +struct i2c_mux_bus { + uint channel; +}; + +/* Find out the mux channel number */ +static int i2c_mux_child_post_bind(struct udevice *dev) +{ + struct i2c_mux_bus *plat = dev_get_parent_platdata(dev); + int channel; + + channel = fdtdec_get_int(gd->fdt_blob, dev->of_offset, "reg", -1); + if (channel < 0) + return -EINVAL; + plat->channel = channel; + + return 0; +} + +/* Find the I2C buses selected by this mux */ +static int i2c_mux_post_bind(struct udevice *mux) +{ + const void *blob = gd->fdt_blob; + int ret; + int offset; + + debug("%s: %s\n", __func__, mux->name); + /* + * There is no compatible string in the sub-nodes, so we must manually + * bind these + */ + for (offset = fdt_first_subnode(blob, mux->of_offset); + offset > 0; + offset = fdt_next_subnode(blob, offset)) { + struct udevice *dev; + const char *name; + + name = fdt_get_name(blob, offset, NULL); + ret = device_bind_driver_to_node(mux, "i2c_mux_bus_drv", name, + offset, &dev); + debug(" - bind ret=%d, %s\n", ret, dev ? dev->name : NULL); + if (ret) + return ret; + } + + return 0; +} + +/* Set up the mux ready for use */ +static int i2c_mux_post_probe(struct udevice *mux) +{ + struct i2c_mux *priv = dev_get_uclass_priv(mux); + int ret; + + debug("%s: %s\n", __func__, mux->name); + priv->selected = -1; + + ret = uclass_get_device_by_phandle(UCLASS_I2C, mux, "i2c-parent", + &priv->i2c_bus); + if (ret) + return ret; + debug("%s: bus=%p/%s\n", __func__, priv->i2c_bus, priv->i2c_bus->name); + + return 0; +} + +int i2c_mux_select(struct udevice *dev) +{ + struct i2c_mux_bus *plat = dev_get_parent_platdata(dev); + struct udevice *mux = dev->parent; + struct i2c_mux_ops *ops = i2c_mux_get_ops(mux); + + if (!ops->select) + return -ENOSYS; + + return ops->select(mux, dev, plat->channel); +} + +int i2c_mux_deselect(struct udevice *dev) +{ + struct i2c_mux_bus *plat = dev_get_parent_platdata(dev); + struct udevice *mux = dev->parent; + struct i2c_mux_ops *ops = i2c_mux_get_ops(mux); + + if (!ops->deselect) + return -ENOSYS; + + return ops->deselect(mux, dev, plat->channel); +} + +static int i2c_mux_bus_set_bus_speed(struct udevice *dev, unsigned int speed) +{ + struct udevice *mux = dev->parent; + struct i2c_mux *priv = dev_get_uclass_priv(mux); + int ret, ret2; + + ret = i2c_mux_select(dev); + if (ret) + return ret; + ret = dm_i2c_set_bus_speed(priv->i2c_bus, speed); + ret2 = i2c_mux_deselect(dev); + + return ret ? ret : ret2; +} + +static int i2c_mux_bus_probe(struct udevice *dev, uint chip_addr, + uint chip_flags) +{ + struct udevice *mux = dev->parent; + struct i2c_mux *priv = dev_get_uclass_priv(mux); + struct dm_i2c_ops *ops = i2c_get_ops(priv->i2c_bus); + int ret, ret2; + + debug("%s: %s, bus %s\n", __func__, dev->name, priv->i2c_bus->name); + if (!ops->probe_chip) + return -ENOSYS; + ret = i2c_mux_select(dev); + if (ret) + return ret; + ret = ops->probe_chip(priv->i2c_bus, chip_addr, chip_flags); + ret2 = i2c_mux_deselect(dev); + + return ret ? ret : ret2; +} + +static int i2c_mux_bus_xfer(struct udevice *dev, struct i2c_msg *msg, + int nmsgs) +{ + struct udevice *mux = dev->parent; + struct i2c_mux *priv = dev_get_uclass_priv(mux); + struct dm_i2c_ops *ops = i2c_get_ops(priv->i2c_bus); + int ret, ret2; + + debug("%s: %s, bus %s\n", __func__, dev->name, priv->i2c_bus->name); + if (!ops->xfer) + return -ENOSYS; + ret = i2c_mux_select(dev); + if (ret) + return ret; + ret = ops->xfer(priv->i2c_bus, msg, nmsgs); + ret2 = i2c_mux_deselect(dev); + + return ret ? ret : ret2; +} + +static const struct dm_i2c_ops i2c_mux_bus_ops = { + .xfer = i2c_mux_bus_xfer, + .probe_chip = i2c_mux_bus_probe, + .set_bus_speed = i2c_mux_bus_set_bus_speed, +}; + +U_BOOT_DRIVER(i2c_mux_bus) = { + .name = "i2c_mux_bus_drv", + .id = UCLASS_I2C, + .per_child_auto_alloc_size = sizeof(struct dm_i2c_chip), + .ops = &i2c_mux_bus_ops, +}; + +UCLASS_DRIVER(i2c_mux) = { + .id = UCLASS_I2C_MUX, + .name = "i2c_mux", + .post_bind = i2c_mux_post_bind, + .post_probe = i2c_mux_post_probe, + .per_device_auto_alloc_size = sizeof(struct i2c_mux), + .per_child_platdata_auto_alloc_size = sizeof(struct i2c_mux_bus), + .child_post_bind = i2c_mux_child_post_bind, +}; diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h index bc057d7..777b101 100644 --- a/include/dm/uclass-id.h +++ b/include/dm/uclass-id.h @@ -35,6 +35,7 @@ enum uclass_id { UCLASS_I2C, /* I2C bus */ UCLASS_I2C_EEPROM, /* I2C EEPROM device */ UCLASS_I2C_GENERIC, /* Generic I2C device */ + UCLASS_I2C_MUX, /* I2C multiplexer */ UCLASS_LED, /* Light-emitting diode (LED) */ UCLASS_LPC, /* x86 'low pin count' interface */ UCLASS_MASS_STORAGE, /* Mass storage device */ diff --git a/include/i2c.h b/include/i2c.h index d191829..6493931 100644 --- a/include/i2c.h +++ b/include/i2c.h @@ -445,6 +445,45 @@ struct dm_i2c_ops { #define i2c_get_ops(dev) ((struct dm_i2c_ops *)(dev)->driver->ops) /** + * struct i2c_mux_ops - operations for an I2C mux + * + * The current mux state is expected to be stored in the mux itself since + * it is the only thing that knows how to make things work. The mux can + * record the current state and then avoid switching unless it is necessary. + * So select() can be skipped if the mux is already in the correct state. + * Also deselect() can be made a nop if required. + */ +struct i2c_mux_ops { + /** + * select() - select one of of I2C buses attached to a mux + * + * This will be called when there is no bus currently selected by the + * mux. This method does not need to deselect the old bus since + * deselect() will be already have been called if necessary. + * + * @mux: Mux device + * @bus: I2C bus to select + * @channel: Channel number correponding to the bus to select + * @return 0 if OK, -ve on error + */ + int (*select)(struct udevice *mux, struct udevice *bus, uint channel); + + /** + * deselect() - select one of of I2C buses attached to a mux + * + * This is used to deselect the currently selected I2C bus. + * + * @mux: Mux device + * @bus: I2C bus to deselect + * @channel: Channel number correponding to the bus to deselect + * @return 0 if OK, -ve on error + */ + int (*deselect)(struct udevice *mux, struct udevice *bus, uint channel); +}; + +#define i2c_mux_get_ops(dev) ((struct i2c_mux_ops *)(dev)->driver->ops) + +/** * i2c_get_chip() - get a device to use to access a chip on a bus * * This returns the device for the given chip address. The device can then |