cr50: Consolidate CCD device enable

Currently, the Cr50 state machines (EC, AP, RDD, bitbang, etc.) manage
their own enabling and disabling of the ports (UART, SPI, etc.)  This
is tricky because the rules for when ports should be enabled are
non-trivial and must be applied in the correct order.  In additionl
the changes all need to be serialized, so that the hardware ends up in
the correct state even if multiple state machines are changing
simultaneously.

Consolidate all of that into chip/g/rdd.c.  The debug command for it
is now 'ccdstate', which just prints the state machines.  This will
allow subsequent renaming of the 'ccdopen', etc. commands to 'ccd
open', etc.

Also include UART bit-banging into that state which must be
consistent.  Previously, it was possible for bit-banging to leave UART
TX connected, instead of returning it to the previous state.

Use better names for CCD config fields for UART.  I'd had them backwards.

BUG=b:62537474
BRANCH=cr50
TEST=manual, with a CR50_DEV=1 image
	1) No servo or CCD
	Pull SERVO_DETECT low (disconnected)
	Pull CCD_MODE_L high (disabled)
	Pull EC_DETECT and AP_DETECT high (on)
	Reboot.  RX is enabled even if cables are disconnected so we buffer.
	ccdstate -> UARTAP UARTEC

	Pull EC_DETECT low.
	ccdstate -> UARTAP

	Pull EC_DETECT high and AP_DETECT low.
	ccdstate -> UARTEC
	Pull AP_DETECT high.
	ccdstate -> UARTAP UARTEC

	2) Servo only still allows UART RX
	Pull SERVO_DETECT high (connected).
	ccdstate -> UARTAP UARTEC

	3) Both servo and CCD prioritizes servo.
	Pull CCD_MODE_L low (enabled).
	ccdstate -> UARTAP UARTEC

	Reboot, to make sure servo wins at boot time.
	ccdstate -> UARTAP UARTEC

	Bit-banging doesn't work when servo is connected.
	bitbang 2 9600 even -> superseded by servo
	bitbang -> disabled
	ccdstate -> UARTAP UARTEC

	4) CCD only allows more ports and remembers we wanted to bit-bang
	Pull SERVO_DETECT low.
	ccdstate --> UARTAP+TX UARTEC+BB I2C SPI
	bitbang 2 disable
	ccdstate --> UARTAP+TX UARTEC+TX I2C SPI

	Reboot and see we don't take over servo ports until we're
	sure servo isn't present.
	ccdstate --> UARTAP UARTEC (for first second)
	ccdstate --> UARTAP+TX UARTEC+TX I2C SPI (after that)

	5) Bit-banging takes over ECTX
	bitbang 2 9600 even
	bitbang -> baud rate 9600, parity even
	ccdstate -> UARTAP+TX UARTEC+BB I2C SPI

	bitbang 2 disable
	ccdstate -> UARTAP+TX UARTEC+TX I2C SPI

	6) Permissions work.  Allow easy access to full console and ccdopen:
	ccdset OpenNoTPMWipe always
	ccdset OpenNoLongPP always
	ccdset GscFullConsole always

	Default when locked is full AP UART EC RO, no I2C or SPI
	ccdlock
	ccdstate -> UARTAP+TX UARTEC

	No EC transmit permission means no bit-banging
	bitbang 2 9600 even
	bitbang -> disabled
	ccdstate -> UARTAP+TX UARTEC

	But it remembers that we wanted to
	ccdopen
	ccdstate -> UARTAP+TX UARTEC+BB I2C SPI
	bitbang 2 disable
	ccdstate -> UARTAP+TX UARTEC+TX I2C SPI

	Try turning on/off permissions
	ccdset UartGscTxECRx always
	ccdlock
	ccdstate -> UARTAP+TX UARTEC+TX

	No read means no write either
	ccdset UartGscRxECTx ifopened
	ccdlock
	ccdstate -> UARTAP+TX
	ccdopen
	ccdset UartGscRXAPTx ifopened
	ccdlock
	ccdstate -> (nothing)

	Check AP transmit permissions too
	ccdopen
	ccdset UartGscRxAPTx always
	ccdset UartGscTxAPRx ifopened
	ccdlock
	ccdstate -> UARTAP

	Check I2C
	ccdopen
	ccdset I2C always
	ccdlock
	ccdstate -> UARTAP I2C

	SPI port is enabled if either EC or AP flash is allowed
	ccdopen
	ccdset flashap always
	ccdlock
	ccdstate -> UARTAP I2C SPI
	ccdopen
	ccdset flashec always
	ccdset flashap ifopened
	ccdlock
	ccdstate -> UARTAP I2C SPI

	Back to defaults
	ccdoops

Change-Id: I641f7ab2354570812e3fb37b470de32e5bd10db7
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/615928
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
(cherry picked from commit a285acd36f898a394b82b8cb865bf60922f7ae2c)
Reviewed-on: https://chromium-review.googlesource.com/656425
Commit-Queue: Vadim Bendebury <vbendeb@chromium.org>
Tested-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>

2 files changed, 73 insertions, 18 deletions

diff --git a/chip/g/uart_bitbang.c b/chip/g/uart_bitbang.c
index b1afb6504c..6d38626b68 100644
--- a/chip/g/uart_bitbang.c
+++ b/chip/g/uart_bitbang.c
@@ -32,6 +32,9 @@
 
 /* Flag indicating whether bit banging is enabled or not. */
 static uint8_t bitbang_enabled;
+/* Flag indicating bit banging is desired.  Allows async enable/disable. */
+static uint8_t bitbang_wanted;
+
 static int rx_buf[RX_BUF_SIZE];
 
 /* Current bitbang context */
@@ -61,23 +64,28 @@ static int is_uart_allowed(int uart)
 
 int uart_bitbang_is_enabled(int uart)
 {
-	return (is_uart_allowed(uart) && !!bitbang_enabled);
+	return (is_uart_allowed(uart) && bitbang_enabled);
+}
+
+int uart_bitbang_is_wanted(int uart)
+{
+	return (is_uart_allowed(uart) && bitbang_wanted);
 }
 
-int uart_bitbang_enable(int uart, int baud_rate, int parity)
+int uart_bitbang_config(int uart, int baud_rate, int parity)
 {
-	/* We only want to bit bang 1 UART at a time. */
+	/* Can't configure when enabled */
 	if (bitbang_enabled)
 		return EC_ERROR_BUSY;
 
 	if (!is_uart_allowed(uart)) {
-		CPRINTF("bit bang config not found for UART%d", uart);
+		CPRINTF("bit bang config not found for UART%d\n", uart);
 		return EC_ERROR_INVAL;
 	}
 
 	/* Check desired properties. */
 	if (!IS_BAUD_RATE_SUPPORTED(baud_rate)) {
-		CPRINTF("Err: invalid baud rate (%d)", baud_rate);
+		CPRINTF("Err: invalid baud rate (%d)\n", baud_rate);
 		return EC_ERROR_INVAL;
 	}
 	bitbang_config.baud_rate = baud_rate;
@@ -89,13 +97,30 @@ int uart_bitbang_enable(int uart, int baud_rate, int parity)
 		break;
 
 	default:
-		CPRINTF("Err: invalid parity '%d'. (0:N, 1:O, 2:E)", parity);
+		CPRINTF("Err: invalid parity '%d'. (0:N, 1:O, 2:E)\n", parity);
 		return EC_ERROR_INVAL;
 	};
 	bitbang_config.htp.parity = parity;
 
-	/* Select the GPIOs instead of the UART block. */
-	uartn_tx_disconnect(bitbang_config.uart);
+	return EC_SUCCESS;
+}
+
+int uart_bitbang_enable(int uart)
+{
+	/* We only want to bit bang 1 UART at a time */
+	if (bitbang_enabled)
+		return EC_ERROR_BUSY;
+
+	/* UART TX must be disconnected first */
+	if (uart_tx_is_connected(uart))
+		return EC_ERROR_BUSY;
+
+	if (!is_uart_allowed(uart)) {
+		CPRINTS("bit bang config not found for UART%d", uart);
+		return EC_ERROR_INVAL;
+	}
+
+	/* Select the GPIOs instead of the UART block */
 	REG32(bitbang_config.tx_pinmux_reg) =
 		bitbang_config.tx_pinmux_regval;
 	gpio_set_flags(bitbang_config.tx_gpio, GPIO_OUT_HIGH);
@@ -126,7 +151,7 @@ int uart_bitbang_enable(int uart, int baud_rate, int parity)
 
 	bitbang_enabled = 1;
 	gpio_enable_interrupt(bitbang_config.rx_gpio);
-	ccprintf("successfully enabled\n");
+	CPRINTS("Bit bang enabled");
 	return EC_SUCCESS;
 }
 
@@ -151,9 +176,9 @@ int uart_bitbang_disable(int uart)
 	/* Gate the microsecond timer since we're done with it. */
 	pmu_clock_dis(PERIPH_TIMEUS);
 
-	/* Reconnect the GPIO to the UART block. */
+	/* Don't need to watch RX */
 	gpio_disable_interrupt(bitbang_config.rx_gpio);
-	uartn_tx_connect(uart);
+	CPRINTS("Bit bang disabled");
 	return EC_SUCCESS;
 }
 
@@ -388,14 +413,17 @@ static int command_bitbang(int argc, char **argv)
 	int uart;
 	int baud_rate;
 	int parity;
+	int rv;
 
 	if (argc > 1) {
 		uart = atoi(argv[1]);
 		if (argc == 3) {
-			if (!strcasecmp("disable", argv[2]))
-				return uart_bitbang_disable(uart);
-			else
-				return EC_ERROR_PARAM2;
+			if (!strcasecmp("disable", argv[2])) {
+				bitbang_wanted = 0;
+				ccd_update_state();
+				return EC_SUCCESS;
+			}
+			return EC_ERROR_PARAM2;
 		}
 
 		if (argc == 4) {
@@ -414,7 +442,16 @@ static int command_bitbang(int argc, char **argv)
 			else
 				return EC_ERROR_PARAM3;
 
-			return uart_bitbang_enable(uart, baud_rate, parity);
+			rv = uart_bitbang_config(uart, baud_rate, parity);
+			if (rv)
+				return rv;
+
+			if (servo_is_connected())
+				ccprintf("Bit banging superseded by servo\n");
+
+			bitbang_wanted = 1;
+			ccd_update_state();
+			return EC_SUCCESS;
 		}
 
 		return EC_ERROR_PARAM_COUNT;
diff --git a/chip/g/uart_bitbang.h b/chip/g/uart_bitbang.h
index f29c35dd34..7a8a33e923 100644
--- a/chip/g/uart_bitbang.h
+++ b/chip/g/uart_bitbang.h
@@ -50,7 +50,9 @@ struct uart_bitbang_properties {
 extern struct uart_bitbang_properties bitbang_config;
 
 /**
- * Enable bit banging mode for a UART.
+ * Configure bit banging mode for a UART.
+ *
+ * If configuration succeeds, then call uart_bitbang_enable() on the port.
  *
  * @param uart: Index of UART to enable bit banging mode.
  * @param baud_rate:  desired baud rate.
@@ -58,7 +60,16 @@ extern struct uart_bitbang_properties bitbang_config;
  *
  * @returns EC_SUCCESS on success, otherwise an error.
  */
-int uart_bitbang_enable(int uart, int baud_rate, int parity);
+int uart_bitbang_config(int uart, int baud_rate, int parity);
+
+/**
+ * Enable bit banging mode for a UART.
+ *
+ * The UART must have been configured first.
+ *
+ * @param uart: Index of UART to disable bit banging mode.
+ */
+int uart_bitbang_enable(int uart);
 
 /**
  * Disable bit banging mode for a UART.
@@ -75,6 +86,13 @@ int uart_bitbang_disable(int uart);
 int uart_bitbang_is_enabled(int uart);
 
 /**
+ * Returns 1 if bit banging mode is wanted for the UART.
+ *
+ * @param uart: Index of UART to query.
+ */
+int uart_bitbang_is_wanted(int uart);
+
+/**
  * TX a character on a UART configured for bit banging mode.
  *
  * @param uart: Index of UART to use.