stm32-USB: USB GPIO control driver

Simple control of GPIOs over USB.

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

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

Change-Id: Ic5deccd1a70080742d5ac745b537ebecd56d7443
Reviewed-on: https://chromium-review.googlesource.com/217528
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>

3 files changed, 201 insertions, 0 deletions

diff --git a/chip/stm32/build.mk b/chip/stm32/build.mk
index b23f044554..1c5081a5da 100644
--- a/chip/stm32/build.mk
+++ b/chip/stm32/build.mk
@@ -39,6 +39,7 @@ chip-$(CONFIG_ADC)+=adc-$(CHIP_FAMILY).o
 chip-$(CONFIG_PWM)+=pwm.o
 chip-$(CONFIG_USB)+=usb.o usb_endpoints.o
 chip-$(CONFIG_USB_CONSOLE)+=usb_console.o
+chip-$(CONFIG_USB_GPIO)+=usb_gpio.o
 chip-$(CONFIG_USB_HID)+=usb_hid.o
 chip-$(CONFIG_USB_MS)+=usb_ms.o usb_ms_scsi.o
 chip-$(CONFIG_USB_POWER_DELIVERY)+=usb_pd_phy.o
diff --git a/chip/stm32/usb_gpio.c b/chip/stm32/usb_gpio.c
new file mode 100644
index 0000000000..027ddadaae
--- /dev/null
+++ b/chip/stm32/usb_gpio.c
@@ -0,0 +1,81 @@
+/* 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 "link_defs.h"
+#include "registers.h"
+#include "usb_gpio.h"
+
+void usb_gpio_tx(struct usb_gpio_config const *config)
+{
+	size_t   i;
+	uint32_t mask  = 1;
+	uint32_t value = 0;
+
+	for (i = 0; i < config->num_gpios; ++i, mask <<= 1)
+		value |= (gpio_get_level(config->gpios[i])) ? mask : 0;
+
+	config->tx_ram[0] = value;
+	config->tx_ram[1] = value >> 16;
+
+	btable_ep[config->endpoint].tx_count = USB_GPIO_TX_PACKET_SIZE;
+
+	/*
+	 * TX packet updated, mark the packet as VALID.
+	 */
+	STM32_TOGGLE_EP(config->endpoint, EP_TX_MASK, EP_TX_VALID, 0);
+}
+
+void usb_gpio_rx(struct usb_gpio_config const *config)
+{
+	size_t   i;
+	uint32_t mask        = 1;
+	uint32_t set_mask    = ((uint32_t)(config->rx_ram[0]) |
+			        (uint32_t)(config->rx_ram[1]) << 16);
+	uint32_t clear_mask  = ((uint32_t)(config->rx_ram[2]) |
+			        (uint32_t)(config->rx_ram[3]) << 16);
+	uint32_t ignore_mask = set_mask & clear_mask;
+
+	if ((btable_ep[config->endpoint].rx_count & 0x3ff) ==
+	    USB_GPIO_RX_PACKET_SIZE) {
+		for (i = 0; i < config->num_gpios; ++i, mask <<= 1) {
+			if (ignore_mask & mask)
+				;
+			else if (set_mask & mask)
+				gpio_set_level(config->gpios[i], 1);
+			else if (clear_mask & mask)
+				gpio_set_level(config->gpios[i], 0);
+		}
+	}
+
+	/*
+	 * RX packet consumed, mark the packet as VALID.
+	 */
+	STM32_TOGGLE_EP(config->endpoint, EP_RX_MASK, EP_RX_VALID, 0);
+}
+
+void usb_gpio_reset(struct usb_gpio_config const *config)
+{
+	int i = config->endpoint;
+
+	btable_ep[i].tx_addr  = usb_sram_addr(config->tx_ram);
+	btable_ep[i].tx_count = USB_GPIO_TX_PACKET_SIZE;
+
+	btable_ep[i].rx_addr  = usb_sram_addr(config->rx_ram);
+	btable_ep[i].rx_count = ((USB_GPIO_RX_PACKET_SIZE / 2) << 10);
+
+	/*
+	 * Initialize TX buffer with zero, the first IN transaction will fill
+	 * this in with a valid value.
+	 */
+	config->tx_ram[0] = 0;
+	config->tx_ram[1] = 0;
+
+	STM32_USB_EP(i) = ((i <<  0) | /* Endpoint Addr*/
+			   (3 <<  4) | /* TX Valid */
+			   (0 <<  9) | /* Bulk EP */
+			   (3 << 12)); /* RX Valid */
+}
diff --git a/chip/stm32/usb_gpio.h b/chip/stm32/usb_gpio.h
new file mode 100644
index 0000000000..2027df9d21
--- /dev/null
+++ b/chip/stm32/usb_gpio.h
@@ -0,0 +1,119 @@
+/* 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.
+ */
+#ifndef CHIP_STM32_USB_GPIO_H
+#define CHIP_STM32_USB_GPIO_H
+
+/* STM32 USB GPIO driver for Chrome EC */
+
+#include "compile_time_macros.h"
+#include "usb.h"
+
+/*
+ * Compile time Per-USB gpio configuration stored in flash.  Instances of this
+ * structure are provided by the user of the USB gpio.  This structure binds
+ * together all information required to operate a USB gpio.
+ */
+struct usb_gpio_config {
+	/*
+	 * Endpoint index, and pointers to the USB packet RAM buffers.
+	 */
+	int endpoint;
+
+	usb_uint *rx_ram;
+	usb_uint *tx_ram;
+
+	/*
+	 * GPIO list
+	 */
+	enum gpio_signal const *gpios;
+	size_t num_gpios;
+};
+
+#define USB_GPIO_RX_PACKET_SIZE 8
+#define USB_GPIO_TX_PACKET_SIZE 4
+
+/*
+ * Convenience macro for defining a USB GPIO driver and its associated state.
+ *
+ * NAME is used to construct the names of the trampoline functions,
+ * usb_gpio_state struct, and usb_gpio_config struct, the latter is just
+ * called NAME.
+ *
+ * INTERFACE is the index of the USB interface to associate with this
+ * GPIO driver.
+ *
+ * ENDPOINT is the index of the USB bulk endpoint used for receiving and
+ * transmitting bytes.
+ */
+#define USB_GPIO_CONFIG(NAME,						\
+			GPIO_LIST,					\
+			INTERFACE,					\
+			ENDPOINT)					\
+	BUILD_ASSERT(ARRAY_SIZE(GPIO_LIST) <= 32);			\
+	static usb_uint CONCAT2(NAME, _ep_rx_buffer)[USB_GPIO_RX_PACKET_SIZE / 2] __usb_ram;	\
+	static usb_uint CONCAT2(NAME, _ep_tx_buffer)[USB_GPIO_TX_PACKET_SIZE / 2] __usb_ram;	\
+	struct usb_gpio_config const NAME = {				\
+		.endpoint  = ENDPOINT,					\
+		.rx_ram    = CONCAT2(NAME, _ep_rx_buffer),		\
+		.tx_ram    = CONCAT2(NAME, _ep_tx_buffer),		\
+		.gpios     = GPIO_LIST,					\
+		.num_gpios = ARRAY_SIZE(GPIO_LIST),			\
+	};								\
+	const struct usb_interface_descriptor				\
+	USB_IFACE_DESC(INTERFACE) = {					\
+		.bLength            = USB_DT_INTERFACE_SIZE,		\
+		.bDescriptorType    = USB_DT_INTERFACE,			\
+		.bInterfaceNumber   = INTERFACE,			\
+		.bAlternateSetting  = 0,				\
+		.bNumEndpoints      = 2,				\
+		.bInterfaceClass    = USB_CLASS_VENDOR_SPEC,		\
+		.bInterfaceSubClass = 0,				\
+		.bInterfaceProtocol = 0,				\
+		.iInterface         = 0,				\
+	};								\
+	const struct usb_endpoint_descriptor				\
+	USB_EP_DESC(INTERFACE, 0) = {					\
+		.bLength          = USB_DT_ENDPOINT_SIZE,		\
+		.bDescriptorType  = USB_DT_ENDPOINT,			\
+		.bEndpointAddress = 0x80 | ENDPOINT,			\
+		.bmAttributes     = 0x02 /* Bulk IN */,			\
+		.wMaxPacketSize   = USB_GPIO_TX_PACKET_SIZE,		\
+		.bInterval        = 10,					\
+	};								\
+	const struct usb_endpoint_descriptor				\
+	USB_EP_DESC(INTERFACE, 1) = {					\
+		.bLength          = USB_DT_ENDPOINT_SIZE,		\
+		.bDescriptorType  = USB_DT_ENDPOINT,			\
+		.bEndpointAddress = ENDPOINT,				\
+		.bmAttributes     = 0x02 /* Bulk OUT */,		\
+		.wMaxPacketSize   = USB_GPIO_RX_PACKET_SIZE,		\
+		.bInterval        = 0,					\
+	};								\
+	static void CONCAT2(NAME, _ep_tx)(void)				\
+	{								\
+		usb_gpio_tx(&NAME);					\
+	}								\
+	static void CONCAT2(NAME, _ep_rx)(void)				\
+	{								\
+		usb_gpio_rx(&NAME);					\
+	}								\
+	static void CONCAT2(NAME, _ep_reset)(void)			\
+	{								\
+		usb_gpio_reset(&NAME);					\
+	}								\
+	USB_DECLARE_EP(ENDPOINT,					\
+		       CONCAT2(NAME, _ep_tx),				\
+		       CONCAT2(NAME, _ep_rx),				\
+		       CONCAT2(NAME, _ep_reset));
+
+/*
+ * These functions are used by the trampoline functions defined above to
+ * connect USB endpoint events with the generic USB GPIO driver.
+ */
+void usb_gpio_tx(struct usb_gpio_config const *config);
+void usb_gpio_rx(struct usb_gpio_config const *config);
+void usb_gpio_reset(struct usb_gpio_config const *config);
+
+#endif /* CHIP_STM32_USB_GPIO_H */