servo_micro: add parity setting

Add a control interface to set parity
for USB-UART bridge.

BRANCH=None
BUG=b:37513705
TEST=parity settable on command line or by servod

Signed-off-by: Nick Sanders <nsanders@chromium.org>
Change-Id: Ib859a70981162be58edfa79c7cb267e0084e05e6
Reviewed-on: https://chromium-review.googlesource.com/564150
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>

board/servo_micro/board.c

@@ -5,6 +5,7 @@
 /* Servo micro board configuration */
 
 #include "common.h"
+#include "console.h"
 #include "ec_version.h"
 #include "gpio.h"
 #include "hooks.h"
@@ -52,14 +53,15 @@ static struct usart_config const usart2 =
 		usart2_to_usb,
 		usb_to_usart2);
 
-USB_STREAM_CONFIG(usart2_usb,
+USB_STREAM_CONFIG_USART_IFACE(usart2_usb,
 	USB_IFACE_USART2_STREAM,
 	USB_STR_USART2_STREAM_NAME,
 	USB_EP_USART2_STREAM,
 	USB_STREAM_RX_SIZE,
 	USB_STREAM_TX_SIZE,
 	usb_to_usart2,
-	usart2_to_usb)
+	usart2_to_usb,
+	usart2)
 
 
 /******************************************************************************
@@ -82,14 +84,15 @@ static struct usart_config const usart3 =
 		usart3_to_usb,
 		usb_to_usart3);
 
-USB_STREAM_CONFIG(usart3_usb,
+USB_STREAM_CONFIG_USART_IFACE(usart3_usb,
 	USB_IFACE_USART3_STREAM,
 	USB_STR_USART3_STREAM_NAME,
 	USB_EP_USART3_STREAM,
 	USB_STREAM_RX_SIZE,
 	USB_STREAM_TX_SIZE,
 	usb_to_usart3,
-	usart3_to_usb)
+	usart3_to_usb,
+	usart3)
 
 
 /******************************************************************************
@@ -112,15 +115,56 @@ static struct usart_config const usart4 =
 		usart4_to_usb,
 		usb_to_usart4);
 
-USB_STREAM_CONFIG(usart4_usb,
+USB_STREAM_CONFIG_USART_IFACE(usart4_usb,
 	USB_IFACE_USART4_STREAM,
 	USB_STR_USART4_STREAM_NAME,
 	USB_EP_USART4_STREAM,
 	USB_STREAM_RX_SIZE,
 	USB_STREAM_TX_SIZE,
 	usb_to_usart4,
-	usart4_to_usb)
+	usart4_to_usb,
+	usart4)
 
+/******************************************************************************
+ * Check parity setting on usarts.
+ */
+static int command_uart_parity(int argc, char **argv)
+{
+	int parity, newparity;
+	struct usart_config const *usart;
+	char *e;
+
+	if ((argc < 2) || (argc > 3))
+		return EC_ERROR_PARAM_COUNT;
+
+	if (!strcasecmp(argv[1], "usart2"))
+		usart = &usart2;
+	else if (!strcasecmp(argv[1], "usart3"))
+		usart = &usart3;
+	else if (!strcasecmp(argv[1], "usart4"))
+		usart = &usart4;
+	else
+		return EC_ERROR_PARAM1;
+
+	if (argc == 3) {
+		parity = strtoi(argv[2], &e, 0);
+		if (*e || (parity < 0) || (parity > 2))
+			return EC_ERROR_PARAM2;
+
+		usart_set_parity(usart, parity);
+	}
+
+	newparity = usart_get_parity(usart);
+	ccprintf("Parity on %s is %d.\n", argv[1], newparity);
+
+	if ((argc == 3) && (newparity != parity))
+		return EC_ERROR_UNKNOWN;
+
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(parity, command_uart_parity,
+			"usart[2|3|4] [0|1|2]",
+			"Set parity on uart");
 
 /******************************************************************************
  * Define the strings used in our USB descriptors.

chip/stm32/registers.h

@@ -222,6 +222,8 @@
 #define STM32_USART_CR1_RXNEIE		(1 << 5)
 #define STM32_USART_CR1_TCIE		(1 << 6)
 #define STM32_USART_CR1_TXEIE		(1 << 7)
+#define STM32_USART_CR1_PS		(1 << 9)
+#define STM32_USART_CR1_PCE		(1 << 10)
 #define STM32_USART_CR1_OVER8		(1 << 15)
 #define STM32_USART_CR2(base)      STM32_USART_REG(base, 0x04)
 #define STM32_USART_CR2_SWAP		(1 << 15)
@@ -264,6 +266,8 @@
 #define STM32_USART_CR1_RXNEIE		(1 << 5)
 #define STM32_USART_CR1_TCIE		(1 << 6)
 #define STM32_USART_CR1_TXEIE		(1 << 7)
+#define STM32_USART_CR1_PS		(1 << 9)
+#define STM32_USART_CR1_PCE		(1 << 10)
 #define STM32_USART_CR1_UE		(1 << 13)
 #define STM32_USART_CR1_OVER8		(1 << 15) /* STM32L only */
 #define STM32_USART_CR2(base)      STM32_USART_REG(base, 0x10)

chip/stm32/usart.c

@@ -102,6 +102,46 @@ void usart_set_baud_f(struct usart_config const *config, int frequency_hz)
 	STM32_USART_BRR(config->hw->base) = div;
 }
 
+int usart_get_parity(struct usart_config const *config)
+{
+	intptr_t base = config->hw->base;
+
+	if (!(STM32_USART_CR1(base) & STM32_USART_CR1_PCE))
+		return 0;
+	if (STM32_USART_CR1(base) & STM32_USART_CR1_PS)
+		return 1;
+	return 2;
+}
+
+void usart_set_parity(struct usart_config const *config, int parity)
+{
+	uint32_t ue;
+	intptr_t base = config->hw->base;
+
+	if ((parity < 0) || (parity > 2))
+		return;
+
+	/* Record active state and disable the UART. */
+	ue = STM32_USART_CR1(base) & STM32_USART_CR1_UE;
+	STM32_USART_CR1(base) &= ~STM32_USART_CR1_UE;
+
+	if (parity) {
+		/* Set parity control enable. */
+		STM32_USART_CR1(base) |= STM32_USART_CR1_PCE;
+		/* Set parity select even/odd bit. */
+		if (parity == 2)
+			STM32_USART_CR1(base) &= ~STM32_USART_CR1_PS;
+		else
+			STM32_USART_CR1(base) |= STM32_USART_CR1_PS;
+	} else {
+		STM32_USART_CR1(base) &=
+			~(STM32_USART_CR1_PCE | STM32_USART_CR1_PS);
+	}
+
+	/* Restore active state. */
+	STM32_USART_CR1(base) |= ue;
+}
+
 void usart_interrupt(struct usart_config const *config)
 {
 	config->tx->interrupt(config);

chip/stm32/usart.h

@@ -197,6 +197,18 @@ void usart_interrupt(struct usart_config const *config);
 void usart_set_baud_f0_l(struct usart_config const *config, int frequency_hz);
 void usart_set_baud_f(struct usart_config const *config, int frequency_hz);
 
+/*
+ * Allow specification of parity for this usart.
+ * parity is 0: none, 1: odd, 2: even.
+ */
+void usart_set_parity(struct usart_config const *config, int parity);
+
+/*
+ * Check parity for this usart.
+ * parity is 0: none, 1: odd, 2: even.
+ */
+int usart_get_parity(struct usart_config const *config);
+
 /*
  * Different families provide different ways of clearing the transmit complete
  * flag.  This function will be provided by the family specific implementation.

chip/stm32/usb-stream.c

@@ -12,6 +12,7 @@
 #include "task.h"
 #include "timer.h"
 #include "util.h"
+#include "usart.h"
 #include "usb_hw.h"
 #include "usb-stream.h"
 
@@ -143,3 +144,38 @@ void usb_stream_reset(struct usb_stream_config const *config)
 			   (0 <<  9) | /* Bulk EP */
 			   (rx_disabled(config) ? EP_RX_NAK : EP_RX_VALID));
 }
+
+int usb_usart_interface(struct usb_stream_config const *config,
+			struct usart_config const *usart,
+			int interface,
+			usb_uint *rx_buf, usb_uint *tx_buf)
+{
+	struct usb_setup_packet req;
+
+	usb_read_setup_packet(rx_buf, &req);
+
+	if (req.bmRequestType != (USB_DIR_OUT |
+				  USB_TYPE_VENDOR |
+				  USB_RECIP_INTERFACE))
+		return -1;
+
+	if (req.wIndex  != interface ||
+	    req.wLength != 0)
+		return -1;
+
+	switch (req.bRequest) {
+	/* Set parity. */
+	case USB_USART_SET_PARITY:
+		usart_set_parity(usart, req.wValue);
+		break;
+
+	/* TODO(nsanders): support reading parity. */
+	/* TODO(nsanders): support baud. */
+	default:
+		return -1;
+	}
+
+	btable_ep[0].tx_count = 0;
+	STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID, EP_STATUS_OUT);
+	return 0;
+}

chip/stm32/usb-stream.h

@@ -16,6 +16,7 @@
 #include "hooks.h"
 #include "producer.h"
 #include "queue.h"
+#include "usart.h"
 #include "usb_descriptor.h"
 #include "usb_hw.h"
 
@@ -230,11 +231,56 @@ extern struct producer_ops const usb_stream_producer_ops;
 			       RX_QUEUE,				\
 			       TX_QUEUE)
 
+/* Declare a utility interface for setting parity/baud. */
+#define USB_USART_IFACE(NAME, INTERFACE, USART_CFG)			\
+	static int CONCAT2(NAME,  _interface_)(usb_uint *rx_buf,	\
+					      usb_uint *tx_buf)		\
+	{ return usb_usart_interface(&NAME, &USART_CFG, INTERFACE,	\
+					rx_buf, tx_buf); }		\
+	USB_DECLARE_IFACE(INTERFACE,					\
+			  CONCAT2(NAME, _interface_))
+
+/* This is a medium version for declaring Google serial endpoints */
+#define USB_STREAM_CONFIG_USART_IFACE(NAME,				\
+				      INTERFACE,			\
+				      INTERFACE_NAME,			\
+				      ENDPOINT,				\
+				      RX_SIZE,				\
+				      TX_SIZE,				\
+				      RX_QUEUE,				\
+				      TX_QUEUE,				\
+				      USART_CFG)			\
+	USB_STREAM_CONFIG_FULL(NAME,					\
+			       INTERFACE,				\
+			       USB_CLASS_VENDOR_SPEC,			\
+			       USB_SUBCLASS_GOOGLE_SERIAL,		\
+			       USB_PROTOCOL_GOOGLE_SERIAL,		\
+			       INTERFACE_NAME,				\
+			       ENDPOINT,				\
+			       RX_SIZE,					\
+			       TX_SIZE,					\
+			       RX_QUEUE,				\
+			       TX_QUEUE);				\
+	USB_USART_IFACE(NAME, INTERFACE, USART_CFG)
+
 /*
  * Handle USB and Queue request in a deferred callback.
  */
 void usb_stream_deferred(struct usb_stream_config const *config);
 
+/*
+ * Handle control interface requests.
+ */
+enum usb_usart {
+	USB_USART_REQ_PARITY = 0,
+	USB_USART_SET_PARITY = 1,
+	USB_USART_REQ_BAUD = 2,
+	USB_USART_SET_BAUD = 3,
+};
+int usb_usart_interface(struct usb_stream_config const *config,
+		    struct usart_config const *usart,
+		    int interface, usb_uint *rx_buf, usb_uint *tx_buf);
+
 /*
  * These functions are used by the trampoline functions defined above to
  * connect USB endpoint events with the generic USB stream driver.