stm32-USB: USB SPI tunnel driver

Simple control of SPI for flashing over USB.

This driver is working, and using the discovery board
with a W25Q16 flash chip attached flashrom can read,
erase, write, and verify the whole chip in 45 seconds.

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

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

Change-Id: I224f1f87cd6adc8b64c17de1df98dae0a9cfa6a5
Reviewed-on: https://chromium-review.googlesource.com/218740
Reviewed-by: Anton Staaf <robotboy@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>

1 files changed, 124 insertions, 0 deletions

diff --git a/chip/stm32/usb_spi.c b/chip/stm32/usb_spi.c
new file mode 100644
index 0000000000..6140f4629b
--- /dev/null
+++ b/chip/stm32/usb_spi.c
@@ -0,0 +1,124 @@
+/* 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 "link_defs.h"
+#include "registers.h"
+#include "spi.h"
+#include "usb.h"
+#include "usb_spi.h"
+
+static int16_t usb_spi_map_error(int error)
+{
+	switch (error) {
+	case EC_SUCCESS:       return usb_spi_success;
+	case EC_ERROR_TIMEOUT: return usb_spi_timeout;
+	case EC_ERROR_BUSY:    return usb_spi_busy;
+	default:               return usb_spi_unknown_error | (error & 0x7fff);
+	}
+}
+
+static uint8_t usb_spi_read_packet(struct usb_spi_config const *config)
+{
+	size_t  i;
+	uint8_t count = btable_ep[config->endpoint].rx_count & 0x3ff;
+
+	/*
+	 * The USB peripheral doesn't support DMA access to its packet
+	 * RAM so we have to copy messages out into a bounce buffer.
+	 */
+	for (i = 0; i < (count + 1) / 2; ++i)
+		config->buffer[i] = config->rx_ram[i];
+
+	/*
+	 * RX packet consumed, mark the packet as VALID.  The master
+	 * could queue up the next command while we process this SPI
+	 * transaction and prepare the response.
+	 */
+	STM32_TOGGLE_EP(config->endpoint, EP_RX_MASK, EP_RX_VALID, 0);
+
+	return count;
+}
+
+static void usb_spi_write_packet(struct usb_spi_config const *config,
+				 uint8_t count)
+{
+	size_t  i;
+
+	/*
+	 * Copy read bytes and status back out of bounce buffer and
+	 * update TX packet state (mark as VALID for master to read).
+	 */
+	for (i = 0; i < (count + 1) / 2; ++i)
+		config->tx_ram[i] = config->buffer[i];
+
+	btable_ep[config->endpoint].tx_count = count;
+
+	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)
+{
+	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;
+
+	if (write_count > USB_SPI_MAX_WRITE_COUNT ||
+	    write_count != (count - 2)) {
+		config->buffer[0] = usb_spi_write_count_invalid;
+	} else if (read_count > USB_SPI_MAX_READ_COUNT) {
+		config->buffer[0] = usb_spi_read_count_invalid;
+	} else {
+		config->buffer[0] = usb_spi_map_error(
+			spi_transaction((uint8_t *)(config->buffer + 1),
+					write_count,
+					(uint8_t *)(config->buffer + 1),
+					read_count));
+	}
+
+	usb_spi_write_packet(config, read_count + 2);
+
+	return 1;
+}
+
+void usb_spi_tx(struct usb_spi_config const *config)
+{
+	STM32_TOGGLE_EP(config->endpoint, EP_TX_MASK, EP_TX_NAK, 0);
+}
+
+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);
+}
+
+void usb_spi_reset(struct usb_spi_config const *config)
+{
+	int endpoint = config->endpoint;
+
+	btable_ep[endpoint].tx_addr  = usb_sram_addr(config->tx_ram);
+	btable_ep[endpoint].tx_count = 0;
+
+	btable_ep[endpoint].rx_addr  = usb_sram_addr(config->rx_ram);
+	btable_ep[endpoint].rx_count =
+		0x8000 | ((USB_MAX_PACKET_SIZE / 32 - 1) << 10);
+
+	STM32_USB_EP(endpoint) = ((endpoint <<  0) | /* Endpoint Addr*/
+				  (2        <<  4) | /* TX NAK */
+				  (0        <<  9) | /* Bulk EP */
+				  (3        << 12)); /* RX Valid */
+}