cmd: dm: allow for selecting uclass and device

The output from "dm tree" or "dm uclass" is a bit annoying
if the number of devices available on the system is huge.
(This is especially true on sandbox when I debug some DM code.)

With this patch, we can specify the uclass name or the device
name that we are interested in in order to limit the output.

For instance,

=> dm uclass usb
uclass 121: usb
0     usb@1 @ 0bcff8b0, seq 1

uclass 124: usb

=> dm tree usb:usb@1
 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 usb           0  [   ]   usb_sandbox           usb@1
 usb_hub       0  [   ]   usb_hub               `-- hub
 usb_emul      0  [   ]   usb_sandbox_hub           `-- hub-emul
 usb_emul      1  [   ]   usb_sandbox_flash             |-- flash-stick@0
 usb_emul      2  [   ]   usb_sandbox_flash             |-- flash-stick@1
 usb_emul      3  [   ]   usb_sandbox_flash             |-- flash-stick@2
 usb_emul      4  [   ]   usb_sandbox_keyb              `-- keyb@3

If you want forward-matching against a uclass or udevice name,
you can specify "-e" option.

=> dm uclass -e usb
uclass 15: usb_emul
0     hub-emul @ 0bcffb00, seq 0
1     flash-stick@0 @ 0bcffc30, seq 1
2     flash-stick@1 @ 0bcffdc0, seq 2
3     flash-stick@2 @ 0bcfff50, seq 3
4     keyb@3 @ 0bd000e0, seq 4

uclass 64: usb_mass_storage

uclass 121: usb
0     usb@1 @ 0bcff8b0, seq 1

uclass 122: usb_dev_generic

uclass 123: usb_hub
0     hub @ 0bcff9b0, seq 0

uclass 124: usb

=> dm tree -e usb
 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 usb           0  [   ]   usb_sandbox           usb@1
 usb_hub       0  [   ]   usb_hub               `-- hub
 usb_emul      0  [   ]   usb_sandbox_hub           `-- hub-emul
 usb_emul      1  [   ]   usb_sandbox_flash             |-- flash-stick@0
 usb_emul      2  [   ]   usb_sandbox_flash             |-- flash-stick@1
 usb_emul      3  [   ]   usb_sandbox_flash             |-- flash-stick@2
 usb_emul      4  [   ]   usb_sandbox_keyb              `-- keyb@3

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/usage/cmd/dm.rst b/doc/usage/cmd/dm.rst
index 74c6b01..12b7ede 100644
--- a/doc/usage/cmd/dm.rst
+++ b/doc/usage/cmd/dm.rst
@@ -12,8 +12,8 @@
     dm devres
     dm drivers
     dm static
-    dm tree [-s]
-    dm uclass
+    dm tree [-s][-e] [uclass name]
+    dm uclass [-e] [udevice name]
 
 Description
 -----------
@@ -127,6 +127,12 @@
 device) are shown sorted in order of uclass ID, so it is easier to find a
 particular device type.
 
+If -e is given, forward-matching against existing devices is
+made and only the matched devices are shown.
+
+If a device name is given, forward-matching against existing devices is
+made and only the matched devices are shown.
+
 dm uclass
 ~~~~~~~~~
 
@@ -140,6 +146,11 @@
 where `n` is the index within the uclass, `a` is the address of the device in
 memory and `s` is the sequence number of the device.
 
+If -e is given, forward-matching against existing uclasses is
+made and only the matched uclasses are shown.
+
+If no uclass name is given, all the uclasses are shown.
+
 
 Examples
 --------
@@ -409,6 +420,15 @@
     nop           8  [   ]   scmi_voltage_domain       `-- regulators
     regulator     5  [   ]   scmi_regulator                |-- reg@0
     regulator     6  [   ]   scmi_regulator                `-- reg@1
+    => dm tree pinc
+    pinctrl       0  [ + ]   sandbox_pinctrl_gpio  pinctrl-gpio
+    gpio          1  [ + ]   sandbox_gpio          |-- base-gpios
+    nop           0  [ + ]   gpio_hog              |   |-- hog_input_active_low
+    nop           1  [ + ]   gpio_hog              |   |-- hog_input_active_high
+    nop           2  [ + ]   gpio_hog              |   |-- hog_output_low
+    nop           3  [ + ]   gpio_hog              |   `-- hog_output_high
+    gpio          2  [   ]   sandbox_gpio          |-- extra-gpios
+    gpio          3  [   ]   sandbox_gpio          `-- pinmux-gpios
     =>
 
 
@@ -487,4 +507,10 @@
     0   * gpio-wdt @ 0301c070, seq 0
     1   * wdt@0 @ 03021710, seq 1
 
+    => dm uclass blk
+    uclass 22: blk
+    0     mmc2.blk @ 0301ca00, seq 0
+    1     mmc1.blk @ 0301cee0, seq 1
+    2     mmc0.blk @ 0301d380, seq 2
+
     =>