usb: add USB console driver

Provide access to the EC console through 2 USB bulk endpoints.
(which can be used through the usbserial driver)

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=none
BUG=none
TEST=run on Fruitpie and use the console over USB

Change-Id: Ia897764f3a030972ee2ed323f293c5fca899765a
Reviewed-on: https://chromium-review.googlesource.com/204167
Reviewed-by: Anton Staaf <robotboy@chromium.org>
Commit-Queue: Vic Yang <victoryang@chromium.org>
Tested-by: Vic Yang <victoryang@chromium.org>

1 files changed, 245 insertions, 0 deletions

diff --git a/chip/stm32/usb_console.c b/chip/stm32/usb_console.c
new file mode 100644
index 0000000000..a8b219bb87
--- /dev/null
+++ b/chip/stm32/usb_console.c
@@ -0,0 +1,245 @@
+/* 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 "config.h"
+#include "console.h"
+#include "link_defs.h"
+#include "printf.h"
+#include "registers.h"
+#include "task.h"
+#include "timer.h"
+#include "util.h"
+#include "usb.h"
+
+/* Console output macro */
+#define CPRINTF(format, args...) cprintf(CC_USB, format, ## args)
+
+#define USB_CONSOLE_TIMEOUT_US (30 * MSEC)
+#define USB_CONSOLE_RX_BUF_SIZE 16
+#define RX_BUF_NEXT(i) (((i) + 1) & (USB_CONSOLE_RX_BUF_SIZE - 1))
+
+static volatile char rx_buf[USB_CONSOLE_RX_BUF_SIZE];
+static volatile int rx_buf_head;
+static volatile int rx_buf_tail;
+
+static int last_tx_ok = 1;
+
+static int is_reset;
+
+/* USB-Serial descriptors */
+const struct usb_interface_descriptor USB_IFACE_DESC(USB_IFACE_CONSOLE) = {
+	.bLength = USB_DT_INTERFACE_SIZE,
+	.bDescriptorType = USB_DT_INTERFACE,
+	.bInterfaceNumber = USB_IFACE_CONSOLE,
+	.bAlternateSetting = 0,
+	.bNumEndpoints = 2,
+	.bInterfaceClass = USB_CLASS_VENDOR_SPEC,
+	.bInterfaceSubClass = 0,
+	.bInterfaceProtocol = 0,
+	.iInterface = 0,
+};
+const struct usb_endpoint_descriptor USB_EP_DESC(USB_IFACE_CONSOLE, 82) = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bEndpointAddress = 0x80 | USB_EP_CON_TX,
+	.bmAttributes = 0x02 /* Bulk IN */,
+	.wMaxPacketSize = USB_MAX_PACKET_SIZE,
+	.bInterval = 10
+};
+const struct usb_endpoint_descriptor USB_EP_DESC(USB_IFACE_CONSOLE, 3) = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bEndpointAddress = USB_EP_CON_RX,
+	.bmAttributes = 0x02 /* Bulk OUT */,
+	.wMaxPacketSize = USB_MAX_PACKET_SIZE,
+	.bInterval = 0
+};
+
+static usb_uint ep_buf_tx[USB_MAX_PACKET_SIZE / 2] __usb_ram;
+static usb_uint ep_buf_rx[USB_MAX_PACKET_SIZE / 2] __usb_ram;
+
+static void con_ep_tx(void)
+{
+	uint16_t ep = STM32_USB_EP(USB_EP_CON_TX);
+	/* clear IT */
+	STM32_USB_EP(USB_EP_CON_TX) = (ep & EP_MASK);
+	return;
+}
+
+static void con_ep_rx(void)
+{
+	int i;
+	for (i = 0; i < (btable_ep[USB_EP_CON_RX].rx_count & 0x3ff); i++) {
+		int rx_buf_next = RX_BUF_NEXT(rx_buf_head);
+		if (rx_buf_next != rx_buf_tail) {
+			/* Not working on old STM32 ... */
+			rx_buf[rx_buf_head] = ((uint8_t *)ep_buf_rx)[i];
+			rx_buf_head = rx_buf_next;
+		}
+	}
+	/* clear IT */
+	STM32_TOGGLE_EP(USB_EP_CON_RX, EP_RX_MASK, EP_RX_VALID, 0);
+	/* wake-up the console task */
+	console_has_input();
+	return;
+}
+
+int usb_getc(void)
+{
+	int c;
+
+	if (rx_buf_tail == rx_buf_head)
+		return -1;
+
+	c = rx_buf[rx_buf_tail];
+	rx_buf_tail = RX_BUF_NEXT(rx_buf_tail);
+	return c;
+}
+
+static int __tx_char(void *context, int c)
+{
+	uint16_t *buf = (uint16_t *)ep_buf_tx;
+	int *tx_idx = context;
+
+	/* Do newline to CRLF translation */
+	if (c == '\n' && __tx_char(context, '\r'))
+		return 1;
+
+	if (*tx_idx > 63)
+		return 1;
+	if (!(*tx_idx & 1))
+		buf[*tx_idx/2] = c;
+	else
+		buf[*tx_idx/2] |= c << 8;
+	(*tx_idx)++;
+
+	return 0;
+}
+
+static void usb_enable_tx(int len)
+{
+	btable_ep[USB_EP_CON_TX].tx_count = len;
+	STM32_TOGGLE_EP(USB_EP_CON_TX, EP_TX_MASK, EP_TX_VALID, 0);
+}
+
+static inline int usb_console_tx_valid(void)
+{
+	return (STM32_USB_EP(USB_EP_CON_TX) & EP_TX_MASK) == EP_TX_VALID;
+}
+
+static int usb_wait_console(void)
+{
+	timestamp_t deadline = get_time();
+	int wait_time_us = 1;
+
+	deadline.val += USB_CONSOLE_TIMEOUT_US;
+
+	/*
+	 * If the USB console is not used, Tx buffer would never free up.
+	 * In this case, let's drop characters immediately instead of sitting
+	 * for some time just to time out. On the other hand, if the last
+	 * Tx is good, it's likely the host is there to receive data, and
+	 * we should wait so that we don't clobber the buffer.
+	 */
+	if (last_tx_ok) {
+		while (usb_console_tx_valid() || !is_reset) {
+			if (timestamp_expired(deadline, NULL)) {
+				last_tx_ok = 0;
+				return EC_ERROR_TIMEOUT;
+			}
+			if (wait_time_us < MSEC)
+				udelay(wait_time_us);
+			else
+				usleep(wait_time_us);
+			wait_time_us *= 2;
+		}
+
+		return EC_SUCCESS;
+	} else {
+		last_tx_ok = !usb_console_tx_valid();
+		return EC_SUCCESS;
+	}
+}
+
+int usb_putc(int c)
+{
+	int ret;
+	int tx_idx = 0;
+
+	ret = usb_wait_console();
+	if (ret)
+		return ret;
+
+	ret = __tx_char(&tx_idx, c);
+	usb_enable_tx(tx_idx);
+
+	return ret;
+}
+
+int usb_puts(const char *outstr)
+{
+	int ret;
+	int tx_idx = 0;
+
+	ret = usb_wait_console();
+	if (ret)
+		return ret;
+
+	/* Put all characters in the output buffer */
+	while (*outstr) {
+		if (__tx_char(&tx_idx, *outstr++) != 0)
+			break;
+	}
+
+	usb_enable_tx(tx_idx);
+
+	/* Successful if we consumed all output */
+	return *outstr ? EC_ERROR_OVERFLOW : EC_SUCCESS;
+}
+
+int usb_vprintf(const char *format, va_list args)
+{
+	int ret;
+	int tx_idx = 0;
+
+	ret = usb_wait_console();
+	if (ret)
+		return ret;
+
+	ret = vfnprintf(__tx_char, &tx_idx, format, args);
+
+	usb_enable_tx(tx_idx);
+	return ret;
+}
+
+static void ep_tx_reset(void)
+{
+	/* Serial Bulk IN endpoint 2 */
+	btable_ep[USB_EP_CON_TX].tx_addr = usb_sram_addr(ep_buf_tx);
+	btable_ep[USB_EP_CON_TX].tx_count = 0;
+	btable_ep[USB_EP_CON_TX].rx_count = 0;
+	STM32_USB_EP(USB_EP_CON_TX) = (USB_EP_CON_TX << 0) /* Endpoint Addr*/ |
+				      (2 << 4) /* TX NAK */ |
+				      (0 << 9) /* Bulk EP */ |
+				      (0 << 12) /* RX Disabled */;
+	is_reset = 1;
+}
+
+static void ep_rx_reset(void)
+{
+	/* Serial Bulk OUT endpoint 3 */
+	btable_ep[USB_EP_CON_RX].rx_addr = usb_sram_addr(ep_buf_rx);
+	btable_ep[USB_EP_CON_RX].tx_count = 0;
+	btable_ep[USB_EP_CON_RX].rx_count =
+		0x8000 | ((USB_MAX_PACKET_SIZE / 32 - 1) << 10);
+	STM32_USB_EP(USB_EP_CON_RX) = (USB_EP_CON_RX << 0) /* Endpoint Addr */ |
+				      (0 << 4) /* TX Disabled */ |
+				      (0 << 9) /* Bulk EP */ |
+				      (3 << 12) /* RX VALID */;
+}
+
+USB_DECLARE_EP(USB_EP_CON_TX, con_ep_tx, con_ep_tx, ep_tx_reset);
+USB_DECLARE_EP(USB_EP_CON_RX, con_ep_rx, con_ep_rx, ep_rx_reset);