dm: sandbox: i2c: Add a new 'emulation parent' uclass

Sandbox i2c works using emulation drivers which are currently children of the i2c device: rtc_0: rtc@43 { reg = <0x43>; compatible = "sandbox-rtc"; emul { compatible = "sandbox,i2c-rtc"; }; }; In this case the emulation device is attached to i2c bus on address 0x43 and provides the Real-Time-Clock (RTC) functionality. However this is not ideal, since every device on an I2C bus has a child device. This is only really the case for sandbox, but we want to avoid special-case code for sandbox. A better approach seems to be to add a separate node on the bus, an 'emulation parent'. This can be given a bogus address (such as 0xff) and hides all the emulators away. Then we can use a phandle to point from the device to the correct emualtor, and only on sandbox. The code to find an emulator does not interfere with normal i2c operation. Add a new UCLASS_I2C_EMUL_PARENT uclass which allows finding an emulator given a bus, and finding a bus given an emulator. This will be used in a follow-on patch. Signed-off-by: Simon Glass <sjg@chromium.org>

dm: sandbox: i2c: Add a new 'emulation parent' uclass
Sandbox i2c works using emulation drivers which are currently children of the i2c device: rtc_0: rtc@43 { reg = <0x43>; compatible = "sandbox-rtc"; emul { compatible = "sandbox,i2c-rtc"; }; }; In this case the emulation device is attached to i2c bus on address 0x43 and provides the Real-Time-Clock (RTC) functionality. However this is not ideal, since every device on an I2C bus has a child device. This is only really the case for sandbox, but we want to avoid special-case code for sandbox. A better approach seems to be to add a separate node on the bus, an 'emulation parent'. This can be given a bogus address (such as 0xff) and hides all the emulators away. Then we can use a phandle to point from the device to the correct emualtor, and only on sandbox. The code to find an emulator does not interfere with normal i2c operation. Add a new UCLASS_I2C_EMUL_PARENT uclass which allows finding an emulator given a bus, and finding a bus given an emulator. This will be used in a follow-on patch. Signed-off-by: Simon Glass <sjg@chromium.org>
Simon Glass
1 parent 25cbb47090
Showing 3 changed files with 99 additions and 0 deletions Side-by-side Diff
drivers/i2c/i2c-emul-uclass.c
include/dm/uclass-id.h
include/i2c.h
@@ -6,9 +6,86 @@
 #include <common.h>
 #include <dm.h>
 #include <i2c.h>
+#include <dm/device-internal.h>
+#include <dm/uclass-internal.h>
  
+/*
+ * i2c emulation works using an 'emul' node at the bus level. Each device in
+ * that node is in the UCLASS_I2C_EMUL uclass, and emulates one i2c device. A
+ * pointer to the device it emulates is in the 'dev' property of the emul device
+ * uclass platdata (struct i2c_emul_platdata), put there by i2c_emul_find().
+ * When sandbox wants an emulator for a device, it calls i2c_emul_find() which
+ * searches for the emulator with the correct address. To find the device for an
+ * emulator, call i2c_emul_get_device().
+ *
+ * The 'emul' node is in the UCLASS_I2C_EMUL_PARENT uclass. We use a separate
+ * uclass so avoid having strange devices on the I2C bus.
+ */
+
+/**
+ * struct i2c_emul_uc_platdata - information about the emulator for this device
+ *
+ * This is used by devices in UCLASS_I2C_EMUL to record information about the
+ * device being emulated. It is accessible with dev_get_uclass_platdata()
+ *
+ * @dev: Device being emulated
+ */
+struct i2c_emul_uc_platdata {
+	struct udevice *dev;
+};
+
+struct udevice *i2c_emul_get_device(struct udevice *emul)
+{
+	struct i2c_emul_uc_platdata *uc_plat = dev_get_uclass_platdata(emul);
+
+	return uc_plat->dev;
+}
+
+int i2c_emul_find(struct udevice *dev, struct udevice **emulp)
+{
+	struct i2c_emul_uc_platdata *uc_plat;
+	struct udevice *emul;
+	int ret;
+
+	ret = uclass_find_device_by_phandle(UCLASS_I2C_EMUL, dev,
+					    "sandbox,emul", &emul);
+	if (ret) {
+		log_err("No emulators for device '%s'\n", dev->name);
+		return ret;
+	}
+	uc_plat = dev_get_uclass_platdata(emul);
+	uc_plat->dev = dev;
+	*emulp = emul;
+
+	return device_probe(emul);
+}
+
 UCLASS_DRIVER(i2c_emul) = {
 	.id		= UCLASS_I2C_EMUL,
 	.name		= "i2c_emul",
+	.per_device_platdata_auto_alloc_size =
+		 sizeof(struct i2c_emul_uc_platdata),
+};
+
+/*
+ * This uclass is a child of the i2c bus. Its platdata is not defined here so
+ * is defined by its parent, UCLASS_I2C, which uses struct dm_i2c_chip. See
+ * per_child_platdata_auto_alloc_size in UCLASS_DRIVER(i2c).
+ */
+UCLASS_DRIVER(i2c_emul_parent) = {
+	.id		= UCLASS_I2C_EMUL_PARENT,
+	.name		= "i2c_emul_parent",
+	.post_bind	= dm_scan_fdt_dev,
+};
+
+static const struct udevice_id i2c_emul_parent_ids[] = {
+	{ .compatible = "sandbox,i2c-emul-parent" },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_emul_parent_drv) = {
+	.name		= "i2c_emul_parent_drv",
+	.id		= UCLASS_I2C_EMUL_PARENT,
+	.of_match	= i2c_emul_parent_ids,
 };
@@ -21,6 +21,7 @@
 	UCLASS_TEST_DUMMY,
 	UCLASS_SPI_EMUL,	/* sandbox SPI device emulator */
 	UCLASS_I2C_EMUL,	/* sandbox I2C device emulator */
+	UCLASS_I2C_EMUL_PARENT,	/* parent for I2C device emulators */
 	UCLASS_PCI_EMUL,	/* sandbox PCI device emulator */
 	UCLASS_USB_EMUL,	/* sandbox USB bus device emulator */
 	UCLASS_AXI_EMUL,	/* sandbox AXI bus device emulator */
@@ -536,6 +536,27 @@
  */
 void i2c_dump_msgs(struct i2c_msg *msg, int nmsgs);
  
+/**
+ * i2c_emul_find() - Find an emulator for an i2c sandbox device
+ *
+ * This looks at the device's 'emul' phandle
+ *
+ * @dev: Device to find an emulator for
+ * @emulp: Returns the associated emulator, if found *
+ * @return 0 if OK, -ENOENT or -ENODEV if not found
+ */
+int i2c_emul_find(struct udevice *dev, struct udevice **emulp);
+
+/**
+ * i2c_emul_get_device() - Find the device being emulated
+ *
+ * Given an emulator this returns the associated device
+ *
+ * @emul: Emulator for the device
+ * @return device that @emul is emulating
+ */
+struct udevice *i2c_emul_get_device(struct udevice *emul);
+
 #ifndef CONFIG_DM_I2C
  
 /*
...	...	@@ -6,9 +6,86 @@
6	6	#include <common.h>
7	7	#include <dm.h>
8	8	#include <i2c.h>
	9	+#include <dm/device-internal.h>
	10	+#include <dm/uclass-internal.h>
9	11
	12	+/*
	13	+ * i2c emulation works using an 'emul' node at the bus level. Each device in
	14	+ * that node is in the UCLASS_I2C_EMUL uclass, and emulates one i2c device. A
	15	+ * pointer to the device it emulates is in the 'dev' property of the emul device
	16	+ * uclass platdata (struct i2c_emul_platdata), put there by i2c_emul_find().
	17	+ * When sandbox wants an emulator for a device, it calls i2c_emul_find() which
	18	+ * searches for the emulator with the correct address. To find the device for an
	19	+ * emulator, call i2c_emul_get_device().
	20	+ *
	21	+ * The 'emul' node is in the UCLASS_I2C_EMUL_PARENT uclass. We use a separate
	22	+ * uclass so avoid having strange devices on the I2C bus.
	23	+ */
	24	+
	25	+/**
	26	+ * struct i2c_emul_uc_platdata - information about the emulator for this device
	27	+ *
	28	+ * This is used by devices in UCLASS_I2C_EMUL to record information about the
	29	+ * device being emulated. It is accessible with dev_get_uclass_platdata()
	30	+ *
	31	+ * @dev: Device being emulated
	32	+ */
	33	+struct i2c_emul_uc_platdata {
	34	+ struct udevice *dev;
	35	+};
	36	+
	37	+struct udevice i2c_emul_get_device(struct udevice emul)
	38	+{
	39	+ struct i2c_emul_uc_platdata *uc_plat = dev_get_uclass_platdata(emul);
	40	+
	41	+ return uc_plat->dev;
	42	+}
	43	+
	44	+int i2c_emul_find(struct udevice dev, struct udevice *emulp)
	45	+{
	46	+ struct i2c_emul_uc_platdata *uc_plat;
	47	+ struct udevice *emul;
	48	+ int ret;
	49	+
	50	+ ret = uclass_find_device_by_phandle(UCLASS_I2C_EMUL, dev,
	51	+ "sandbox,emul", &emul);
	52	+ if (ret) {
	53	+ log_err("No emulators for device '%s'\n", dev->name);
	54	+ return ret;
	55	+ }
	56	+ uc_plat = dev_get_uclass_platdata(emul);
	57	+ uc_plat->dev = dev;
	58	+ *emulp = emul;
	59	+
	60	+ return device_probe(emul);
	61	+}
	62	+
10	63	UCLASS_DRIVER(i2c_emul) = {
11	64	.id = UCLASS_I2C_EMUL,
12	65	.name = "i2c_emul",
	66	+ .per_device_platdata_auto_alloc_size =
	67	+ sizeof(struct i2c_emul_uc_platdata),
	68	+};
	69	+
	70	+/*
	71	+ * This uclass is a child of the i2c bus. Its platdata is not defined here so
	72	+ * is defined by its parent, UCLASS_I2C, which uses struct dm_i2c_chip. See
	73	+ * per_child_platdata_auto_alloc_size in UCLASS_DRIVER(i2c).
	74	+ */
	75	+UCLASS_DRIVER(i2c_emul_parent) = {
	76	+ .id = UCLASS_I2C_EMUL_PARENT,
	77	+ .name = "i2c_emul_parent",
	78	+ .post_bind = dm_scan_fdt_dev,
	79	+};
	80	+
	81	+static const struct udevice_id i2c_emul_parent_ids[] = {
	82	+ { .compatible = "sandbox,i2c-emul-parent" },
	83	+ { }
	84	+};
	85	+
	86	+U_BOOT_DRIVER(i2c_emul_parent_drv) = {
	87	+ .name = "i2c_emul_parent_drv",
	88	+ .id = UCLASS_I2C_EMUL_PARENT,
	89	+ .of_match = i2c_emul_parent_ids,
13	90	};
...	...	@@ -21,6 +21,7 @@
21	21	UCLASS_TEST_DUMMY,
22	22	UCLASS_SPI_EMUL, /* sandbox SPI device emulator */
23	23	UCLASS_I2C_EMUL, /* sandbox I2C device emulator */
	24	+ UCLASS_I2C_EMUL_PARENT, /* parent for I2C device emulators */
24	25	UCLASS_PCI_EMUL, /* sandbox PCI device emulator */
25	26	UCLASS_USB_EMUL, /* sandbox USB bus device emulator */
26	27	UCLASS_AXI_EMUL, /* sandbox AXI bus device emulator */
...	...	@@ -536,6 +536,27 @@
536	536	*/
537	537	void i2c_dump_msgs(struct i2c_msg *msg, int nmsgs);
538	538
	539	+/**
	540	+ * i2c_emul_find() - Find an emulator for an i2c sandbox device
	541	+ *
	542	+ * This looks at the device's 'emul' phandle
	543	+ *
	544	+ * @dev: Device to find an emulator for
	545	+ * @emulp: Returns the associated emulator, if found *
	546	+ * @return 0 if OK, -ENOENT or -ENODEV if not found
	547	+ */
	548	+int i2c_emul_find(struct udevice dev, struct udevice *emulp);
	549	+
	550	+/**
	551	+ * i2c_emul_get_device() - Find the device being emulated
	552	+ *
	553	+ * Given an emulator this returns the associated device
	554	+ *
	555	+ * @emul: Emulator for the device
	556	+ * @return device that @emul is emulating
	557	+ */
	558	+struct udevice i2c_emul_get_device(struct udevice emul);
	559	+
539	560	#ifndef CONFIG_DM_I2C
540	561
541	562	/*