[U-Boot] [PATCH v2 08/17] dm: i2c: Add a uclass for I2C

Simon Glass
2014-11-11T17:46:24Z

The uclass implements the same operations as the current I2C framework but
makes some changes to make it fit driver model better:

- Remove the chip address from API calls
- Remove the address length from API calls
- Remove concept of 'current' I2C bus
- Drop all existing init functions

Signed-off-by: Simon Glass <sjg@chromium.org>
---

Changes in v2:
- Fix cihp typo
- Implement generic I2C devices to allow 'i2c probe' on unknown devices
- Return the probed device from i2c_probe()
- Set the bus speed after the bus is probed
- Add some debugging for generic I2C device binding
- Add a 'deblock' method to recover an I2C bus stuck in mid-transaction
- Add a helper function to find a chip on a particular bus number

drivers/i2c/Makefile | 1 +
drivers/i2c/i2c-uclass.c | 275 +++++++++++++++++++++++++++++++++++++++++++
include/config_fallbacks.h | 6 +
include/dm/uclass-id.h | 2 +
include/i2c.h | 288 +++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 572 insertions(+)
create mode 100644 drivers/i2c/i2c-uclass.c

diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index d067897..25f0f19 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -4,6 +4,7 @@
#
# SPDX-License-Identifier: GPL-2.0+
#
+obj-$(CONFIG_DM_I2C) += i2c-uclass.o

obj-$(CONFIG_BFIN_TWI_I2C) += bfin-twi_i2c.o
obj-$(CONFIG_I2C_MV) += mv_i2c.o
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
new file mode 100644
index 0000000..9436dfa
--- /dev/null
+++ b/drivers/i2c/i2c-uclass.c
@@ -0,0 +1,275 @@
+/*
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <malloc.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/root.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int i2c_read(struct udevice *dev, uint addr, uint8_t *buffer, int len)
+{
+ struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+ struct udevice *bus = dev_get_parent(dev);
+ struct dm_i2c_ops *ops = i2c_get_ops(bus);
+
+ if (!ops->read)
+ return -ENOSYS;
+
+ return ops->read(bus, chip->chip_addr, addr, chip->addr_len, buffer,
+ len);
+}
+
+int i2c_write(struct udevice *dev, uint addr, const uint8_t *buffer, int len)
+{
+ struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+ struct udevice *bus = dev_get_parent(dev);
+ struct dm_i2c_ops *ops = i2c_get_ops(bus);
+
+ if (!ops->write)
+ return -ENOSYS;
+
+ return ops->write(bus, chip->chip_addr, addr, chip->addr_len, buffer,
+ len);
+}
+
+static int i2c_bind_driver(struct udevice *bus, uint chip_addr,
+ struct udevice **devp)
+{
+ struct dm_i2c_chip *chip;
+ char name[30], *str;
+ struct udevice *dev;
+ int ret;
+
+ snprintf(name, sizeof(name), "generic_%x", chip_addr);
+ str = strdup(name);
+ ret = device_bind_driver(bus, "i2c_generic_drv", str, &dev);
+ debug("%s: device_bind_driver: ret=%d\n", __func__, ret);
+ if (ret)
+ goto err_bind;
+
+ /* Tell the device what we know about it */
+ chip = calloc(1, sizeof(struct dm_i2c_chip));
+ if (!chip) {
+ ret = -ENOMEM;
+ goto err_mem;
+ }
+ chip->chip_addr = chip_addr;
+ chip->addr_len = 1; /* we assume */
+ ret = device_probe_child(dev, chip);
+ debug("%s: device_probe_child: ret=%d\n", __func__, ret);
+ free(chip);
+ if (ret)
+ goto err_probe;
+
+ *devp = dev;
+ return 0;
+
+err_probe:
+err_mem:
+ device_unbind(dev);
+err_bind:
+ free(str);
+ return ret;
+}
+
+int i2c_get_chip(struct udevice *bus, uint chip_addr, struct udevice **devp)
+{
+ struct udevice *dev;
+
+ debug("%s: Searching bus '%s' for address %02x: ", __func__,
+ bus->name, chip_addr);
+ for (device_find_first_child(bus, &dev); dev;
+ device_find_next_child(&dev)) {
+ struct dm_i2c_chip store;
+ struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+ int ret;
+
+ if (!chip) {
+ chip = &store;
+ i2c_chip_ofdata_to_platdata(gd->fdt_blob,
+ dev->of_offset, chip);
+ }
+ if (chip->chip_addr == chip_addr) {
+ ret = device_probe(dev);
+ debug("found, ret=%d\n", ret);
+ if (ret)
+ return ret;
+ *devp = dev;
+ return 0;
+ }
+ }
+ debug("not found\n");
+ return i2c_bind_driver(bus, chip_addr, devp);
+}
+
+int i2c_get_chip_for_busnum(int busnum, int chip_addr, struct udevice **devp)
+{
+ struct udevice *bus;
+ int ret;
+
+ ret = uclass_get_device_by_seq(UCLASS_I2C, busnum, &bus);
+ if (ret) {
+ debug("Cannot find I2C bus %d\n", busnum);
+ return ret;
+ }
+ ret = i2c_get_chip(bus, chip_addr, devp);
+ if (ret) {
+ debug("Cannot find I2C chip %02x on bus %d\n", chip_addr,
+ busnum);
+ return ret;
+ }
+
+ return 0;
+}
+
+int i2c_probe(struct udevice *bus, uint chip_addr, struct udevice **devp)
+{
+ struct dm_i2c_ops *ops = i2c_get_ops(bus);
+ int ret;
+
+ *devp = NULL;
+ if (!ops->probe)
+ return -ENODEV;
+
+ /* First probe that chip */
+ ret = ops->probe(bus, chip_addr);
+ debug("%s: bus='%s', address %02x, ret=%d\n", __func__, bus->name,
+ chip_addr, ret);
+ if (ret)
+ return ret;
+
+ /* The chip was found, see if we have a driver, and probe it */
+ ret = i2c_get_chip(bus, chip_addr, devp);
+ debug("%s: i2c_get_chip: ret=%d\n", __func__, ret);
+ if (!ret || ret != -ENODEV)
+ return ret;
+
+ return i2c_bind_driver(bus, chip_addr, devp);
+}
+
+int i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
+{
+ struct dm_i2c_ops *ops = i2c_get_ops(bus);
+ struct dm_i2c_bus *i2c = bus->uclass_priv;
+ int ret;
+
+ if (ops->set_bus_speed) {
+ ret = ops->set_bus_speed(bus, speed);
+ if (ret)
+ return ret;
+ }
+ i2c->speed_hz = speed;
+
+ return 0;
+}
+
+/*
+ * i2c_get_bus_speed:
+ *
+ * Returns speed of selected I2C bus in Hz
+ */
+int i2c_get_bus_speed(struct udevice *bus)
+{
+ struct dm_i2c_ops *ops = i2c_get_ops(bus);
+ struct dm_i2c_bus *i2c = bus->uclass_priv;
+
+ if (!ops->set_bus_speed)
+ return i2c->speed_hz;
+
+ return ops->get_bus_speed(bus);
+}
+
+int i2c_set_addr_len(struct udevice *dev, uint addr_len)
+{
+ struct udevice *bus = dev->parent;
+ struct dm_i2c_chip *chip = dev_get_parentdata(dev);
+ struct dm_i2c_ops *ops = i2c_get_ops(bus);
+ int ret;
+
+ if (addr_len > 3)
+ return -EINVAL;
+ if (ops->set_addr_len) {
+ ret = ops->set_addr_len(dev, addr_len);
+ if (ret)
+ return ret;
+ }
+ chip->addr_len = addr_len;
+
+ return 0;
+}
+
+int i2c_deblock(struct udevice *bus)
+{
+ struct dm_i2c_ops *ops = i2c_get_ops(bus);
+
+ /*
+ * We could implement a software deblocking here if we could get
+ * access to the GPIOs used by I2C, and switch them to GPIO mode
+ * and then back to I2C. This is somewhat beyond our powers in
+ * driver model at present, so for now just fail.
+ *
+ * See https://patchwork.ozlabs.org/patch/399040/
+ */
+ if (!ops->deblock)
+ return -ENOSYS;
+
+ return ops->deblock(bus);
+}
+
+int i2c_chip_ofdata_to_platdata(const void *blob, int node,
+ struct dm_i2c_chip *chip)
+{
+ chip->addr_len = 1; /* default */
+ chip->chip_addr = fdtdec_get_int(gd->fdt_blob, node, "reg", -1);
+ if (chip->chip_addr == -1) {
+ debug("%s: I2C Node '%s' has no 'reg' property\n", __func__,
+ fdt_get_name(blob, node, NULL));
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int i2c_post_probe(struct udevice *dev)
+{
+ struct dm_i2c_bus *i2c = dev->uclass_priv;
+
+ i2c->speed_hz = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
+ "clock-frequency", 100000);
+
+ return i2c_set_bus_speed(dev, i2c->speed_hz);
+}
+
+int i2c_post_bind(struct udevice *dev)
+{
+ /* Scan the bus for devices */
+ return dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset, false);
+}
+
+UCLASS_DRIVER(i2c) = {
+ .id = UCLASS_I2C,
+ .name = "i2c",
+ .per_device_auto_alloc_size = sizeof(struct dm_i2c_bus),
+ .post_bind = i2c_post_bind,
+ .post_probe = i2c_post_probe,
+};
+
+UCLASS_DRIVER(i2c_generic) = {
+ .id = UCLASS_I2C_GENERIC,
+ .name = "i2c_generic",
+};
+
+U_BOOT_DRIVER(i2c_generic_drv) = {
+ .name = "i2c_generic_drv",
+ .id = UCLASS_I2C_GENERIC,
+};
diff --git a/include/config_fallbacks.h b/include/config_fallbacks.h
index 7d8daa2..91a0a43 100644
--- a/include/config_fallbacks.h
+++ b/include/config_fallbacks.h
@@ -87,4 +87,10 @@
#undef CONFIG_IMAGE_FORMAT_LEGACY
#endif

+#ifdef CONFIG_DM_I2C
+# ifdef CONFIG_SYS_I2C
+# error "Cannot define CONFIG_SYS_I2C when CONFIG_DM_I2C is used"
+# endif
+#endif
+
#endif /* __CONFIG_FALLBACKS_H */
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index a8944c9..43514bc 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -28,6 +28,8 @@ enum uclass_id {
UCLASS_SPI_GENERIC, /* Generic SPI flash target */
UCLASS_SPI_FLASH, /* SPI flash */
UCLASS_CROS_EC, /* Chrome OS EC */
+ UCLASS_I2C, /* I2C bus */
+ UCLASS_I2C_GENERIC, /* Generic I2C device */

UCLASS_COUNT,
UCLASS_INVALID = -1,
diff --git a/include/i2c.h b/include/i2c.h
index 1b4078e..d36afbc 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -18,6 +18,291 @@
#define _I2C_H_

/*
+ * For now there are essentially two parts to this file - driver model
+ * here at the top, and the older code below (with CONFIG_SYS_I2C being
+ * most recent). The plan is to migrate everything to driver model.
+ * The driver model structures and API are separate as they are different
+ * enough as to be incompatible for compilation purposes.
+ */
+
+#ifdef CONFIG_DM_I2C
+
+/**
+ * struct dm_i2c_chip - information about an i2c chip
+ *
+ * An I2C chip is a device on the I2C bus. It sits at a particular address
+ * and normally supports 7-bit or 10-bit addressing.
+ *
+ * To obtain this structure, use dev_get_parentdata(dev) where dev is the
+ * chip to examine.
+ *
+ * @chip_addr: Chip address on bus
+ * @addr_len: Address length in bytes (normally 1 for 7-bit address)
+ * @emul: Emulator for this chip address (only used for emulation)
+ */
+struct dm_i2c_chip {
+ uint chip_addr;
+ uint addr_len;
+#ifdef CONFIG_SANDBOX
+ struct udevice *emul;
+#endif
+};
+
+/**
+ * struct dm_i2c_bus- information about an i2c bus
+ *
+ * An I2C bus contains 0 or more chips on it, each at its own address. The
+ * bus can operate at different speeds (measured in Hz, typically 100KHz
+ * or 400KHz).
+ *
+ * To obtain this structure, use bus->uclass_priv where bus is the I2C
+ * bus udevice.
+ *
+ * @speed_hz: Bus speed in hertz (typically 100000)
+ */
+struct dm_i2c_bus {
+ int speed_hz;
+};
+
+/**
+ * i2c_read() - read bytes from an I2C chip
+ *
+ * To obtain an I2C device (called a 'chip') given the I2C bus address you
+ * can use i2c_get_chip(). To obtain a bus by bus number use
+ * uclass_get_device_by_seq(UCLASS_I2C, <bus number>).
+ *
+ * To set the address length of a devce use i2c_set_addr_len(). It
+ * defaults to 1.
+ *
+ * @dev: Chip to read from
+ * @offset: Offset within chip to start reading
+ * @buffer: Place to put data
+ * @len: Number of bytes to read
+ *
+ * @return 0 on success, -ve on failure
+ */
+int i2c_read(struct udevice *dev, uint offset, uint8_t *buffer,
+ int len);
+
+/**
+ * i2c_write() - write bytes to an I2C chip
+ *
+ * See notes for i2c_read() above.
+ *
+ * @dev: Chip to write to
+ * @offset: Offset within chip to start writing
+ * @buffer: Buffer containing data to write
+ * @len: Number of bytes to write
+ *
+ * @return 0 on success, -ve on failure
+ */
+int i2c_write(struct udevice *dev, uint offset, const uint8_t *buffer,
+ int len);
+
+/**
+ * i2c_probe() - probe a particular chip address
+ *
+ * This can be useful to check for the existence of a chip on the bus.
+ * It is typically implemented by writing the chip address to the bus
+ * and checking that the chip replies with an ACK.
+ *
+ * @bus: Bus to probe
+ * @chip_addr: 7-bit address to probe (10-bit and others are not supported)
+ * @devp: Returns the device found, or NULL if none
+ * @return 0 if a chip was found at that address, -ve if not
+ */
+int i2c_probe(struct udevice *bus, uint chip_addr, struct udevice **devp);
+
+/**
+ * i2c_set_bus_speed() - set the speed of a bus
+ *
+ * @bus: Bus to adjust
+ * @speed: Requested speed in Hz
+ * @return 0 if OK, -EINVAL for invalid values
+ */
+int i2c_set_bus_speed(struct udevice *bus, unsigned int speed);
+
+/**
+ * i2c_get_bus_speed() - get the speed of a bus
+ *
+ * @bus: Bus to check
+ * @return speed of selected I2C bus in Hz, -ve on error
+ */
+int i2c_get_bus_speed(struct udevice *bus);
+
+/**
+ * i2c_set_addr_len() - set the address length of a chip
+ *
+ * Typically addresses are 7 bits (so @addr_len should be 1 which is the
+ * default). For 10-bit addresses use a value of 2. Some drivers and
+ * chips may support 0 and 3 also.
+ *
+ * @dev: Chip to adjust
+ * @addr_len: New address length value (typically 1 or 2)
+ * @return 0 if OK, -EINVAL if value is unsupported, other -ve value on error
+ */
+int i2c_set_addr_len(struct udevice *dev, uint addr_len);
+
+/**
+ * i2c_deblock() - recover a bus that is in an unknown state
+ *
+ * See the deblock() method in 'struct dm_i2c_ops' for full information
+ *
+ * @bus: Bus to recover
+ * @return 0 if OK, -ve on error
+ */
+int i2c_deblock(struct udevice *bus);
+
+/**
+ * struct dm_i2c_ops - driver operations for I2C uclass
+ *
+ * Drivers should support these operations unless otherwise noted. These
+ * operations are intended to be used by uclass code, not directly from
+ * other code.
+ */
+struct dm_i2c_ops {
+ /**
+ * read() - read from a chip
+ *
+ * @bus: Bus to read from
+ * @chip_addr: Chip address to read from
+ * @alen: Length of chip address in bytes
+ * @offset: Offset within chip to start reading
+ * @buffer: Place to put data
+ * @len: Number of bytes to read
+ */
+ int (*read)(struct udevice *bus, uint chip_addr, uint alen,
+ uint offset, uint8_t *buffer, int len);
+
+ /**
+ * write() - write bytes to a chip
+ *
+ * @dev: Device to write to
+ * @chip_addr: Chip address to read from
+ * @alen: Length of chip address in bytes
+ * @offset: Offset within chip to start writing
+ * @buffer: Buffer containing data to write
+ * @len: Number of bytes to write
+ *
+ * @return 0 on success, -ve on failure
+ */
+ int (*write)(struct udevice *bus, uint chip_addr, uint alen,
+ uint offset, const uint8_t *buffer, int len);
+
+ /**
+ * probe() - probe a particular chip address (recommended)
+ *
+ * This function is optional but should be implemented since it is
+ * an expected feature of the I2C subsystem.
+ *
+ * @bus: Bus to probe
+ * @chip_addr: 7-bit address to probe
+ * @return 0 if a chip was found at that address, -ve if not
+ */
+ int (*probe)(struct udevice *bus, uint chip_addr);
+
+ /**
+ * set_bus_speed() - set the speed of a bus (optional)
+ *
+ * The bus speed value will be updated by the uclass if this function
+ * does not return an error.
+ *
+ * @bus: Bus to adjust
+ * @speed: Requested speed in Hz
+ * @return 0 if OK, -INVAL for invalid values
+ */
+ int (*set_bus_speed)(struct udevice *bus, unsigned int speed);
+
+ /**
+ * get_bus_speed() - get the speed of a bus (optional)
+ *
+ * Normally this can be provided by the uclass, but if you want your
+ * driver to check the bus speed by looking at the hardware, you can
+ * implement that here.
+ *
+ * @bus: Bus to check
+ * @return speed of selected I2C bus in Hz, -ve on error
+ */
+ int (*get_bus_speed)(struct udevice *bus);
+
+ /**
+ * set_addr_len() - set the address length of a chip (optional)
+ *
+ * This is generally implemented by the uclass, but drivers can
+ * check the value to ensure that unsupported options are not used.
+ * If provided, this method will always be called when the address
+ * length changes from the default of 1.
+ *
+ * @dev: Chip to adjust
+ * @addr_len: New address length value (typically 1 or 2)
+ * @return 0 if OK, -INVAL if value is unsupported
+ */
+ int (*set_addr_len)(struct udevice *dev, uint addr_len);
+
+ /**
+ * deblock() - recover a bus that is in an unknown state
+ *
+ * I2C is a synchronous protocol and resets of the processor in the
+ * middle of an access can block the I2C Bus until a powerdown of
+ * the full unit is done. This is because slaves can be stuck
+ * waiting for addition bus transitions for a transaction that will
+ * never complete. Resetting the I2C master does not help. The only
+ * way is to force the bus through a series of transitions to make
+ * sure that all slaves are done with the transaction. This method
+ * performs this 'deblocking' if support by the driver.
+ *
+ * This method is optional.
+ */
+ int (*deblock)(struct udevice *bus);
+};
+
+#define i2c_get_ops(dev) ((struct dm_i2c_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
+ * be used with calls to i2c_read(), i2c_write(), i2c_probe(), etc.
+ *
+ * @bus: Bus to examine
+ * @chip_addr: Chip address for the new device
+ * @devp: Returns pointer to new device if found or -ENODEV if not
+ * found
+ */
+int i2c_get_chip(struct udevice *bus, uint chip_addr, struct udevice **devp);
+
+/**
+ * i2c_get_chip() - get a device to use to access a chip on a bus number
+ *
+ * This returns the device for the given chip address on a particular bus
+ * number.
+ *
+ * @busnum: Bus number to examine
+ * @chip_addr: Chip address for the new device
+ * @devp: Returns pointer to new device if found or -ENODEV if not
+ * found
+ */
+int i2c_get_chip_for_busnum(int busnum, int chip_addr, struct udevice **devp);
+
+/**
+ * i2c_chip_ofdata_to_platdata() - Decode standard I2C platform data
+ *
+ * This decodes the chip address from a device tree node and puts it into
+ * its dm_i2c_chip structure. This should be called in your driver's
+ * ofdata_to_platdata() method.
+ *
+ * @blob: Device tree blob
+ * @node: Node offset to read from
+ * @spi: Place to put the decoded information
+ */
+int i2c_chip_ofdata_to_platdata(const void *blob, int node,
+ struct dm_i2c_chip *chip);
+
+#endif
+
+#ifndef CONFIG_DM_I2C
+
+/*
* WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
*
* The implementation MUST NOT use static or global variables if the
@@ -451,4 +736,7 @@ int i2c_get_bus_num_fdt(int node);
* @return 0 if port was reset, -1 if not found
*/
int i2c_reset_port_fdt(const void *blob, int node);
+
+#endif /* !CONFIG_DM_I2C */
+
#endif /* _I2C_H_ */
--
2.1.0.rc2.206.gedb03e5