sandbox: update documents regarding spi_sf

Since the commit 1289e96797 ("sandbox: spi: Drop command-line SPI
option"), "--spi_sf" command line option is no longer supported.

So update the following documents to sync them up with the change.
	doc/arch/sandbox.rst
	doc/SPI/README.sandbox-spi

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

doc/SPI/README.sandbox-spi

@@ -2,59 +2,37 @@ Sandbox SPI/SPI Flash Implementation
 ====================================
 
 U-Boot supports SPI and SPI flash emulation in sandbox. This must be enabled
-using the --spi_sf paramter when starting U-Boot.
+via a device tree.
 
 For example:
 
-$ make O=sandbox sandbox_config
+	spi@0 {
-$ make O=sandbox
+		#address-cells = <1>;
-$ ./sandbox/u-boot --spi_sf 0:0:W25Q128:b/chromeos_peach/out/image.bin
+		#size-cells = <0>;
-
+		reg = <0 1>;
-The four parameters to spi_sf are:
+		compatible = "sandbox,spi";
-
+		cs-gpios = <0>, <&gpio_a 0>;
-   SPI bus number (typically 0)
+		spi.bin@0 {
-   SPI chip select number (typically 0)
+			reg = <0>;
-   SPI chip to emulate
+			compatible = "spansion,m25p16", "jedec,spi-nor";
-   File containing emulated data
+			spi-max-frequency = <40000000>;
+			sandbox,filename = "spi.bin";
+		};
+	};
 
 Supported chips are W25Q16 (2MB), W25Q32 (4MB) and W25Q128 (16MB). Once
 U-Boot it started you can use 'sf' commands as normal. For example:
 
-$ ./b/sandbox/u-boot --spi_sf 0:0:W25Q128:b/chromeos_peach/out/image.bin \
+$ dd if=/dev/zero of=spi.bin bs=1M count=2
-	-c "sf probe; sf test 0 100000; sf read 0 1000 1000; \
+$ u-boot -T
-		sf erase 1000 1000; sf write 0 1000 1000"
-
-
-U-Boot 2013.10-00237-gd4e0fdb (Nov 07 2013 - 20:08:15)
-
-DRAM:  128 MiB
-Using default environment
-
-In:    serial
-Out:   serial
-Err:   serial
-SF: Detected W25Q128BV with page size 256 Bytes, erase size 4 KiB, total 16 MiB
-SPI flash test:
-0 erase: 1 ticks, 1024000 KiB/s 8192.000 Mbps
-1 check: 2 ticks, 512000 KiB/s 4096.000 Mbps
-2 write: 6 ticks, 170666 KiB/s 1365.328 Mbps
-3 read: 0 ticks, 1048576000 KiB/s -201326.-592 Mbps
-Test passed
-0 erase: 1 ticks, 1024000 KiB/s 8192.000 Mbps
-1 check: 2 ticks, 512000 KiB/s 4096.000 Mbps
-2 write: 6 ticks, 170666 KiB/s 1365.328 Mbps
-3 read: 0 ticks, 1048576000 KiB/s -201326.-592 Mbps
-SF: 4096 bytes @ 0x1000 Read: OK
-SF: 4096 bytes @ 0x1000 Erased: OK
-SF: 4096 bytes @ 0x1000 Written: OK
-
 
 Since the SPI bus is fully implemented as well as the SPI flash connected to
 it, you can also use low-level SPI commands to access the flash. For example
 this reads the device ID from the emulated chip:
 
 => sspi 0 32 9f
-FFEF4018
+SF: Detected m25p16 with page size 256 Bytes, erase size 64 KiB, total 2 MiB
+FF202015
 
 
 Simon Glass

doc/arch/sandbox.rst

@@ -316,19 +316,29 @@ SPI Emulation
 
 Sandbox supports SPI and SPI flash emulation.
 
-This is controlled by the spi_sf argument, the format of which is::
+The device can be enabled via a device tree, for example::
 
-   bus:cs:device:file
+    spi@0 {
+            #address-cells = <1>;
+            #size-cells = <0>;
+            reg = <0 1>;
+            compatible = "sandbox,spi";
+            cs-gpios = <0>, <&gpio_a 0>;
+            spi.bin@0 {
+                    reg = <0>;
+                    compatible = "spansion,m25p16", "jedec,spi-nor";
+                    spi-max-frequency = <40000000>;
+                    sandbox,filename = "spi.bin";
+            };
+    };
 
-   bus    - SPI bus number
+The file must be created in advance::
-   cs     - SPI chip select number
-   device - SPI device emulation name
-   file   - File on disk containing the data
 
-For example::
+   $ dd if=/dev/zero of=spi.bin bs=1M count=2
+   $ u-boot -T
 
-   dd if=/dev/zero of=spi.bin bs=1M count=4
+Here, you can use "-T" or "-D" option to specify test.dtb or u-boot.dtb,
-   ./u-boot --spi_sf 0:0:M25P16:spi.bin
+respectively, or "-d <file>" for your own dtb.
 
 With this setup you can issue SPI flash commands as normal::
 
@@ -346,22 +356,6 @@ also use low-level SPI commands::
 This is issuing a READ_ID command and getting back 20 (ST Micro) part
 0x2015 (the M25P16).
 
-Drivers are connected to a particular bus/cs using sandbox's state
-structure (see the 'spi' member). A set of operations must be provided
-for each driver.
-
-
-Configuration settings for the curious are:
-
-CONFIG_SANDBOX_SPI_MAX_BUS:
-  The maximum number of SPI buses supported by the driver (default 1).
-
-CONFIG_SANDBOX_SPI_MAX_CS:
-  The maximum number of chip selects supported by the driver (default 10).
-
-CONFIG_SPI_IDLE_VAL:
-  The idle value on the SPI bus
-
 
 Block Device Emulation
 ----------------------