USB-SPI: Switch from task to deferred function

The task based approach made sense when it looked like
there would be a case closed debugging task to handle
multiple bridges (SPI/I2C/USART...).  I'm not convinced
anymore that that task will be needed, so this
simplification seems good.

Signed-off-by: Anton Staaf <robotboy@chromium.org>

BRANCH=None
BUG=None
TEST=make buildall -j

Change-Id: Ic431c287c28d10252246fe9f507d9c5fcc64a077
Reviewed-on: https://chromium-review.googlesource.com/232733
Tested-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>

6 files changed, 23 insertions, 63 deletions

diff --git a/board/discovery-stm32f072/board.c b/board/discovery-stm32f072/board.c
index 99e0af0b1d..c6a9b3c8a3 100644
--- a/board/discovery-stm32f072/board.c
+++ b/board/discovery-stm32f072/board.c
@@ -87,9 +87,13 @@ void usb_spi_board_disable(struct usb_spi_config const *config)
 	gpio_config_module(MODULE_SPI_MASTER, 0);
 }
 
+USB_SPI_CONFIG(usb_spi, USB_IFACE_SPI, USB_EP_SPI);
+
 /* Initialize board. */
 static void board_init(void)
 {
 	gpio_enable_interrupt(GPIO_USER_BUTTON);
+
+	usb_spi_enable(&usb_spi, 1);
 }
 DECLARE_HOOK(HOOK_INIT, board_init, HOOK_PRIO_DEFAULT);
diff --git a/board/discovery-stm32f072/build.mk b/board/discovery-stm32f072/build.mk
index 7a40d5fc10..d8a22a6ad5 100644
--- a/board/discovery-stm32f072/build.mk
+++ b/board/discovery-stm32f072/build.mk
@@ -10,4 +10,4 @@ CHIP:=stm32
 CHIP_FAMILY:=stm32f0
 CHIP_VARIANT:=stm32f07x
 
-board-y=board.o echo.o spi.o
+board-y=board.o echo.o
diff --git a/board/discovery-stm32f072/ec.tasklist b/board/discovery-stm32f072/ec.tasklist
index 73f7aa6835..6a623f151c 100644
--- a/board/discovery-stm32f072/ec.tasklist
+++ b/board/discovery-stm32f072/ec.tasklist
@@ -19,5 +19,4 @@
 #define CONFIG_TASK_LIST \
 	TASK_ALWAYS(HOOKS,   hook_task,    NULL, TASK_STACK_SIZE) \
 	TASK_ALWAYS(CONSOLE, console_task, NULL, TASK_STACK_SIZE) \
-	TASK_ALWAYS(USB_SPI, usb_spi_task, NULL, TASK_STACK_SIZE) \
 	TASK_ALWAYS(ECHO,    echo_task,    NULL, TASK_STACK_SIZE)
diff --git a/board/discovery-stm32f072/spi.c b/board/discovery-stm32f072/spi.c
deleted file mode 100644
index b768bb42bc..0000000000
--- a/board/discovery-stm32f072/spi.c
+++ /dev/null
@@ -1,29 +0,0 @@
-/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-#include "common.h"
-#include "gpio.h"
-#include "registers.h"
-#include "spi.h"
-#include "task.h"
-#include "usb_spi.h"
-
-void usb_spi_ready(struct usb_spi_config const *config)
-{
-	task_wake(TASK_ID_USB_SPI);
-}
-
-USB_SPI_CONFIG(usb_spi, USB_IFACE_SPI, USB_EP_SPI, usb_spi_ready)
-
-void usb_spi_task(void)
-{
-	usb_spi_enable(&usb_spi. 1);
-
-	while (1) {
-		task_wait_event(-1);
-
-		while (usb_spi_service_request(&usb_spi))
-			;
-	}
-}
diff --git a/chip/stm32/usb_spi.c b/chip/stm32/usb_spi.c
index f0e163cb1b..24b8a530d7 100644
--- a/chip/stm32/usb_spi.c
+++ b/chip/stm32/usb_spi.c
@@ -59,20 +59,12 @@ static void usb_spi_write_packet(struct usb_spi_config const *config,
 	STM32_TOGGLE_EP(config->endpoint, EP_TX_MASK, EP_TX_VALID, 0);
 }
 
-static int rx_valid(struct usb_spi_config const *config)
-{
-	return (STM32_USB_EP(config->endpoint) & EP_RX_MASK) == EP_RX_VALID;
-}
-
-int usb_spi_service_request(struct usb_spi_config const *config)
+void usb_spi_deferred(struct usb_spi_config const *config)
 {
 	uint8_t count;
 	uint8_t write_count;
 	uint8_t read_count;
 
-	if (rx_valid(config))
-		return 0;
-
 	count       = usb_spi_read_packet(config);
 	write_count = (config->buffer[0] >> 0) & 0xff;
 	read_count  = (config->buffer[0] >> 8) & 0xff;
@@ -93,8 +85,6 @@ int usb_spi_service_request(struct usb_spi_config const *config)
 	}
 
 	usb_spi_write_packet(config, read_count + 2);
-
-	return 1;
 }
 
 void usb_spi_tx(struct usb_spi_config const *config)
@@ -105,7 +95,8 @@ void usb_spi_tx(struct usb_spi_config const *config)
 void usb_spi_rx(struct usb_spi_config const *config)
 {
 	STM32_TOGGLE_EP(config->endpoint, EP_RX_MASK, EP_RX_NAK, 0);
-	config->ready(config);
+
+	hook_call_deferred(config->deferred, 0);
 }
 
 void usb_spi_reset(struct usb_spi_config const *config)
diff --git a/chip/stm32/usb_spi.h b/chip/stm32/usb_spi.h
index 4917c16f0b..5da35c91f6 100644
--- a/chip/stm32/usb_spi.h
+++ b/chip/stm32/usb_spi.h
@@ -8,6 +8,7 @@
 /* STM32 USB SPI driver for Chrome EC */
 
 #include "compile_time_macros.h"
+#include "hooks.h"
 #include "usb.h"
 
 /*
@@ -95,18 +96,16 @@ struct usb_spi_config {
 	int endpoint;
 
 	/*
+	 * Deferred function to call to handle SPI request.
+	 */
+	void (*deferred)(void);
+
+	/*
 	 * Pointers to USB packet RAM and bounce buffer.
 	 */
 	uint16_t *buffer;
 	usb_uint *rx_ram;
 	usb_uint *tx_ram;
-
-	/*
-	 * Callback to notify managing task that a new SPI request has been
-	 * received.  This should wake up a task that will eventually call
-	 * the usb_spi_service_request function.
-	 */
-	void (*ready)(struct usb_spi_config const *config);
 };
 
 /*
@@ -120,16 +119,14 @@ struct usb_spi_config {
  *
  * ENDPOINT is the index of the USB bulk endpoint used for receiving and
  * transmitting bytes.
- *
- * READY callback function for command reception notification.
  */
 #define USB_SPI_CONFIG(NAME,						\
 		       INTERFACE,					\
-		       ENDPOINT,					\
-		       READY)						\
+		       ENDPOINT)					\
 	static uint16_t CONCAT2(NAME, _buffer_)[USB_MAX_PACKET_SIZE / 2]; \
 	static usb_uint CONCAT2(NAME, _ep_rx_buffer_)[USB_MAX_PACKET_SIZE / 2] __usb_ram; \
 	static usb_uint CONCAT2(NAME, _ep_tx_buffer_)[USB_MAX_PACKET_SIZE / 2] __usb_ram; \
+	static void CONCAT2(NAME, _deferred_)(void);			\
 	struct usb_spi_state CONCAT2(NAME, _state_) = {			\
 		.disabled = 1,						\
 		.enabled  = 0,						\
@@ -138,10 +135,10 @@ struct usb_spi_config {
 		.state     = &CONCAT2(NAME, _state_),			\
 		.interface = INTERFACE,					\
 		.endpoint  = ENDPOINT,					\
+		.deferred  = CONCAT2(NAME, _deferred_),			\
 		.buffer    = CONCAT2(NAME, _buffer_),			\
 		.rx_ram    = CONCAT2(NAME, _ep_rx_buffer_),		\
 		.tx_ram    = CONCAT2(NAME, _ep_tx_buffer_),		\
-		.ready     = READY,					\
 	};								\
 	const struct usb_interface_descriptor				\
 	USB_IFACE_DESC(INTERFACE) = {					\
@@ -184,17 +181,15 @@ struct usb_spi_config {
 					      usb_uint *tx_buf)		\
 	{ return usb_spi_interface(&NAME, rx_buf, tx_buf); }		\
 	USB_DECLARE_IFACE(INTERFACE,					\
-			  CONCAT2(NAME, _interface_));
+			  CONCAT2(NAME, _interface_));			\
+	static void CONCAT2(NAME, _deferred_)(void)			\
+	{ usb_spi_deferred(&NAME); }					\
+	DECLARE_DEFERRED(CONCAT2(NAME, _deferred_));
 
 /*
- * Check for a new request and process it synchronously, the SPI transaction
- * will complete before this function returns.
- *
- * Returns:
- *     1: request serviced
- *     0: no request waiting
+ * Handle SPI request in a deferred callback.
  */
-int usb_spi_service_request(struct usb_spi_config const *config);
+void usb_spi_deferred(struct usb_spi_config const *config);
 
 /*
  * Set the enable state for the USB-SPI bridge.