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

Simon Glass sjg at chromium.org
Tue Nov 11 18:46:24 CET 2014


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 at 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



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