[ot] hw/opentitan: ot_usbdev: Initial implementation of the block

Signed-off-by: Douglas Reis <[email protected]>
Signed-off-by: Amaury Pouly <[email protected]>

Author: engdoreis

docs/opentitan/earlgrey.md

@@ -269,6 +269,13 @@ There are two modes to handle address remapping, with different limitations:
 * `-device <name>,bus=<bus>,address=<address>` can be used to attach devices at a specific address
   to one of the three I2C buses. The buses are named `ot-i2c0`, `ot-i2c1`, and `ot-i2c2`.
 
+### USBDEV
+
+* `-chardev pty,id=usbdev` can be used to connect to the usbdev driver.
+* `-global ot-usbdev.vbus-mode=<mode>` can be used to select the VBUS mode.
+
+See the [USBDEV documentation](usbdev.md)] for more details.
+
 ## Useful debugging options
 
 ### Device log traces

docs/opentitan/usbdev.md

@@ -0,0 +1,23 @@
+# OpenTitan USBDEV
+
+## `usb` Chardev
+
+The USBDEV driver exposes a chardev with ID `usbdev` which can used to control some aspects of the emulation.
+Once connected, the driver accepts textual commands.
+Each command must end with a newline.
+The following commands are recognized:
+- `vbus_on`: turn on VBUS, see [#VBUS-handling](VBUS handling) for more details.
+- `vbus_off`: turn off VBUS, see [#VBUS-handling](VBUS handling) for more details.
+
+## VBUS handling
+
+On a real machine, the VBUS sense pin is usually connected to the VBUS connector so
+that the chip can detect when a cable is plugged. For the purpose of emulation, a different
+approach needs to be taken. The driver supports several mode of operations which are controlled
+by the `vbus-mode` string property which can be set on the command-line by
+`-global ot-usbdev.vbus-mode=<mode>`. The following modes are supported:
+
+- `vbus-override`: in this mode, the VBUS sense pin is entirely managed over the `usbdev` chardev.
+  By default, the sense pin will be set to level low. The `vbus_on` and `vbus_off` commands
+  can be used to change the value of the sense pin. Note that in this mode, the VBUS sense signal
+  will be completely independent of the presence of a USB host.

hw/opentitan/Kconfig

@@ -191,6 +191,9 @@ config OT_TIMER
 config OT_UART
     bool
 
+config OT_USBDEV
+    bool
+
 config OT_UNIMP
     bool
 

hw/opentitan/meson.build

@@ -61,3 +61,4 @@ system_ss.add(when: 'CONFIG_OT_UNIMP', if_true: files('ot_unimp.c'))
 riscv_ss.add(when: 'CONFIG_OT_VMAPPER', if_true: files('ot_vmapper.c'))
 
 subdir('otbn')
+subdir('usbdev')

hw/opentitan/trace-events

@@ -629,6 +629,14 @@ ot_uart_io_read_out(const char *id, uint32_t addr, const char *regname, uint32_t
 ot_uart_io_write(const char *id, uint32_t addr, const char *regname, uint32_t val, uint32_t pc) "%s: addr=0x%02x (%s), val=0x%x, pc=0x%x"
 ot_uart_irqs(const char *id, uint32_t active, uint32_t mask, uint32_t eff) "%s: act:0x%08x msk:0x%08x eff:0x%08x"
 
+# ot_usbdev.c
+
+ot_usbdev_io_read_out(const char *id, uint32_t addr, const char *regname, uint32_t val, uint32_t pc) "%s: addr=0x%02x (%s), val=0x%x, pc=0x%x"
+ot_usbdev_io_write(const char *id, uint32_t addr, const char *regname, uint32_t val, uint32_t pc) "%s: addr=0x%02x (%s), val=0x%x, pc=0x%x"
+ot_usbdev_irqs(const char *id, uint32_t active, uint32_t mask, uint32_t eff) "%s: act:0x%08x msk:0x%08x eff:0x%08x"
+ot_usbdev_reset(const char *id, const char *stage) "%s: %s"
+ot_usbdev_chr_process_cmd(const char *id, const char *cmd) "%s: %s"
+
 # ot_unimp.c
 
 ot_unimp_irq(const char *id, unsigned ix, bool lvl) "%s: #%u = %u"

hw/opentitan/usbdev/meson.build

@@ -0,0 +1,7 @@
+system_ss.add(
+    when: 'CONFIG_OT_USBDEV',
+    if_true: files(
+        'ot_usbdev.c',
+        'ot_usbdev_state.c'
+    )
+)