libpayload: ipq808x: introduce uart driver

This adds a UART driver for the ipq8064 controller. It still does not
quite work in the receive direction - the receive FIFO returns read
data in 32 bit chunks, which means that 4 keys need to be pressed
before a character pops out of the driver (and it reports it as a
single character).

This issue is being addressed separately, the driver is being checked
in to facilitate concurrent development.

BUG=chrome-os-partner:27784, chrome-os-partner:29313

TEST=with deptcharge modifications in place, the AP148 board comes up
     to the depthcharge prompt:

Starting depthcharge on storm...

Original-Change-Id: Ief2cfcca73494be5c4147881144470078adcefb8
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/202045
Original-Reviewed-by: Deepa Dinamani <deepad@codeaurora.org>
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit 4499318fb9a4e663c504d7c41380ccf2aa89da29)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I3e07d7568c20c0e570222971ff219de3a6d9b7cc
Reviewed-on: http://review.coreboot.org/8061
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

2 files changed, 364 insertions, 0 deletions

diff --git a/payloads/libpayload/drivers/Makefile.inc b/payloads/libpayload/drivers/Makefile.inc
index d46bb11541..538a8a61c4 100644
--- a/payloads/libpayload/drivers/Makefile.inc
+++ b/payloads/libpayload/drivers/Makefile.inc
@@ -36,6 +36,7 @@ libc-$(CONFIG_LP_SPEAKER) += speaker.c
 libc-$(CONFIG_LP_8250_SERIAL_CONSOLE) += serial/8250.c
 libc-$(CONFIG_LP_S5P_SERIAL_CONSOLE) += serial/s5p.c
 libc-$(CONFIG_LP_TEGRA_SERIAL_CONSOLE) += serial/tegra.c
+libc-$(CONFIG_LP_IPQ806X_SERIAL_CONSOLE) += serial/ipq806x.c
 
 libc-$(CONFIG_LP_PC_KEYBOARD) += keyboard.c
 
diff --git a/payloads/libpayload/drivers/serial/ipq806x.c b/payloads/libpayload/drivers/serial/ipq806x.c
new file mode 100644
index 0000000000..834389ec0e
--- /dev/null
+++ b/payloads/libpayload/drivers/serial/ipq806x.c
@@ -0,0 +1,363 @@
+/*
+ * Copyright (c) 2014 Chromium OS authors
+ */
+
+#include <libpayload.h>
+
+enum IPQ_UART_DM_PARITY_MODE {
+        IPQ_UART_DM_NO_PARITY,
+        IPQ_UART_DM_ODD_PARITY,
+        IPQ_UART_DM_EVEN_PARITY,
+        IPQ_UART_DM_SPACE_PARITY
+};
+
+/* UART Stop Bit Length */
+enum IPQ_UART_DM_STOP_BIT_LEN {
+        IPQ_UART_DM_SBL_9_16,
+        IPQ_UART_DM_SBL_1,
+        IPQ_UART_DM_SBL_1_9_16,
+        IPQ_UART_DM_SBL_2
+};
+
+/* UART Bits per Char */
+enum IPQ_UART_DM_BITS_PER_CHAR {
+        IPQ_UART_DM_5_BPS,
+        IPQ_UART_DM_6_BPS,
+        IPQ_UART_DM_7_BPS,
+        IPQ_UART_DM_8_BPS
+};
+
+#define IPQ_UART_DM_CR(base)		(((u8 *)(base)) + 0x10)
+#define IPQ_UART_DM_DMEN(base)		(((u8 *)(base)) + 0x3C)
+#define IPQ_UART_DM_DMRX(base)		(((u8 *)(base)) + 0x34)
+#define IPQ_UART_DM_HCR(base)		(((u8 *)(base)) + 0x24)
+#define IPQ_UART_DM_IMR(base)		(((u8 *)(base)) + 0x14)
+#define IPQ_UART_DM_IPR(base)		(((u8 *)(base)) + 0x18)
+#define IPQ_UART_DM_IRDA(base)		(((u8 *)(base)) + 0x38)
+#define IPQ_UART_DM_MISR(base)	 	(((u8 *)(base)) + 0x10)
+#define IPQ_UART_DM_MR1(base)		(((u8 *)(base)) + 0x00)
+#define IPQ_UART_DM_MR2(base)		(((u8 *)(base)) + 0x04)
+#define IPQ_UART_DM_NO_CHARS_FOR_TX(base) (((u8 *)(base)) + 0x040)
+#define IPQ_UART_DM_RF(base, x)		(((u8 *)(base)) + 0x70 + 4*(x))
+#define IPQ_UART_DM_RFWR(base)		(((u8 *)(base)) + 0x20)
+#define IPQ_UART_DM_RX_TOTAL_SNAP(base)	(((u8 *)(base)) + 0x38)
+#define IPQ_UART_DM_SR(base)		(((u8 *)(base)) + 0x008)
+#define IPQ_UART_DM_TF(base, x)		(((u8 *)(base)) + 0x70 + 4*(x))
+#define IPQ_UART_DM_TFWR(base)		(((u8 *)(base)) + 0x1C)
+
+#define IPQ_UART_DM_TXLEV               (1 << 0)
+#define IPQ_UART_DM_TX_READY            (1 << 7)
+
+#define IPQ_UART_DM_CR_CH_CMD_LSB(x)    ((x & 0x0f) << 4)
+#define IPQ_UART_DM_CR_CH_CMD_MSB(x)    ((x >> 4 ) << 11 )
+#define IPQ_UART_DM_CR_CH_CMD(x)        (IPQ_UART_DM_CR_CH_CMD_LSB(x)\
+                                             | IPQ_UART_DM_CR_CH_CMD_MSB(x))
+
+#define IPQ_UART_DM_CR_GENERAL_CMD(x)   ((x) << 8)
+
+#define IPQ_UART_DM_8_N_1_MODE          (IPQ_UART_DM_NO_PARITY | \
+                                             (IPQ_UART_DM_SBL_1 << 2) | \
+                                             (IPQ_UART_DM_8_BPS << 4))
+#define IPQ_UART_DM_CR_RX_ENABLE        (1 << 0)
+#define IPQ_UART_DM_CR_TX_ENABLE        (1 << 2)
+#define IPQ_UART_DM_CMD_RESET_RX        IPQ_UART_DM_CR_CH_CMD(1)
+#define IPQ_UART_DM_CMD_RESET_TX        IPQ_UART_DM_CR_CH_CMD(2)
+#define IPQ_UART_DM_CMD_RESET_ERR_STAT  IPQ_UART_DM_CR_CH_CMD(3)
+#define IPQ_UART_DM_CMD_RES_STALE_INT   IPQ_UART_DM_CR_CH_CMD(8)
+#define IPQ_UART_DM_CMD_RES_TX_ERR      IPQ_UART_DM_CR_CH_CMD(10)
+#define IPQ_UART_DM_GCMD_ENA_STALE_EVT   IPQ_UART_DM_CR_GENERAL_CMD(5)
+#define IPQ_UART_DM_RXSTALE             (1 << 3)
+#define IPQ_UART_DM_IMR_ENABLED         (IPQ_UART_DM_TX_READY | \
+                                              IPQ_UART_DM_TXLEV    | \
+                                              IPQ_UART_DM_RXSTALE)
+#define IPQ_UART_DM_TFW_VALUE           0
+#define IPQ_UART_DM_RFW_VALUE           1
+#define IPQ_UART_DM_DMRX_DEF_VALUE	0x220
+#define IPQ_UART_DM_SR_TXEMT            (1 << 3)
+#define IPQ_UART_DM_SR_UART_OVERRUN     (1 << 4)
+#define IPQ_UART_DM_E_SUCCESS           0
+#define IPQ_UART_DM_E_INVAL             3
+#define IPQ_UART_DM_E_RX_NOT_READY      5
+
+#define IPQ_UART_DM_STALE_TIMEOUT_LSB   0x0f
+
+static struct console_input_driver consin = {};
+static struct console_output_driver consout = {};
+
+#define FIFO_DATA_SIZE	4
+
+static void  *base_uart_addr;
+
+/*
+ * All constants lifted from u-boot's
+ * board/qcom/ipq806x_cdp/ipq806x_board_param.h
+ */
+static unsigned int msm_boot_uart_dm_init(void *uart_dm_base);
+
+/* Number of pending received characters */
+static int uart_ready_data_count;
+
+/* Received data as it came from 32 bit wide FIFO */
+static unsigned int uart_rx_fifo_word;
+
+/**
+ * msm_boot_uart_dm_init_rx_transfer - Init Rx transfer
+ * @uart_dm_base: UART controller base address
+ */
+static unsigned int msm_boot_uart_dm_init_rx_transfer(void *uart_dm_base)
+{
+	/* Reset receiver */
+	writel(IPQ_UART_DM_CMD_RESET_RX,
+		IPQ_UART_DM_CR(uart_dm_base));
+
+	/* Enable receiver */
+	writel(IPQ_UART_DM_CR_RX_ENABLE,
+		IPQ_UART_DM_CR(uart_dm_base));
+	writel(IPQ_UART_DM_DMRX_DEF_VALUE,
+		IPQ_UART_DM_DMRX(uart_dm_base));
+
+	/* Clear stale event */
+	writel(IPQ_UART_DM_CMD_RES_STALE_INT,
+		IPQ_UART_DM_CR(uart_dm_base));
+
+	/* Enable stale event */
+	writel(IPQ_UART_DM_GCMD_ENA_STALE_EVT,
+		IPQ_UART_DM_CR(uart_dm_base));
+
+	return IPQ_UART_DM_E_SUCCESS;
+}
+
+/**
+ * Reads a word from the RX FIFO or returns not ready.
+ */
+static unsigned msm_boot_uart_dm_read(void)
+{
+	static int total_rx_data = 0;
+	static int rx_data_read = 0;
+	void  *base = base_uart_addr;
+	uint32_t status_reg;
+
+	/* RXSTALE means RX FIFO is not empty. */
+	status_reg = readl(IPQ_UART_DM_MISR(base));
+	if (!(status_reg & IPQ_UART_DM_RXSTALE))
+		return IPQ_UART_DM_E_RX_NOT_READY;
+
+	/* Check for Overrun error. We'll just reset Error Status */
+	if (readl(IPQ_UART_DM_SR(base)) &
+			IPQ_UART_DM_SR_UART_OVERRUN) {
+		writel(IPQ_UART_DM_CMD_RESET_ERR_STAT,
+			IPQ_UART_DM_CR(base));
+		total_rx_data = rx_data_read = 0;
+		msm_boot_uart_dm_init(base);
+		return IPQ_UART_DM_E_RX_NOT_READY;
+	}
+
+	/* Clear stale event. */
+	writel(IPQ_UART_DM_CMD_RES_STALE_INT, IPQ_UART_DM_CR(base));
+
+	/* Read UART_DM_RX_TOTAL_SNAP for actual number of bytes received */
+	if (total_rx_data == 0)
+		total_rx_data =  readl(IPQ_UART_DM_RX_TOTAL_SNAP(base));
+
+	/* Data available in FIFO; read a word. */
+	uart_rx_fifo_word = readl(IPQ_UART_DM_RF(base, 0));
+
+	/*
+	 * TODO(vbendeb): this is wrong and will be addressed shortly: there
+	 * should be no zeros returned from the FIFO in case there are
+	 * received characters (we don't expect to be receiving zeros).
+	 * See http://crosbug.com/p/29313
+	 */
+	if (uart_rx_fifo_word == 0) {
+		return IPQ_UART_DM_E_RX_NOT_READY;
+	}
+
+	/* increment the total count of chars we've read so far */
+	rx_data_read += FIFO_DATA_SIZE;
+
+	/* Actual count of valid data in word */
+	uart_ready_data_count =
+		((total_rx_data < rx_data_read) ?
+		 (FIFO_DATA_SIZE - (rx_data_read - total_rx_data)) :
+		 FIFO_DATA_SIZE);
+
+	/* If there are still data left in FIFO we'll read them before
+	 * initializing RX Transfer again
+	 */
+	if (rx_data_read < total_rx_data)
+		return IPQ_UART_DM_E_SUCCESS;
+
+	msm_boot_uart_dm_init_rx_transfer(base);
+	total_rx_data = rx_data_read = 0;
+
+	return IPQ_UART_DM_E_SUCCESS;
+}
+
+void serial_putchar(unsigned data)
+{
+	int num_of_chars = 0;
+	unsigned tx_data = 0;
+	void *base = base_uart_addr;
+
+	if (data == '\n') {
+		num_of_chars++;
+		tx_data = '\r';
+	}
+
+	tx_data  |= data << (8 * num_of_chars++);
+
+        /* Wait until transmit FIFO is empty. */
+        while (!(readl(IPQ_UART_DM_SR(base)) &
+		 IPQ_UART_DM_SR_TXEMT))
+		udelay(1);
+
+        /*
+	 * TX FIFO is ready to accept new character(s). First write number of
+	 * characters to be transmitted.
+	 */
+        writel(num_of_chars, IPQ_UART_DM_NO_CHARS_FOR_TX(base));
+
+	/* And now write the character(s) */
+	writel(tx_data, IPQ_UART_DM_TF(base, 0));
+}
+
+/*
+ * msm_boot_uart_dm_reset - resets UART controller
+ * @base: UART controller base address
+ */
+static unsigned int msm_boot_uart_dm_reset(void *base)
+{
+	writel(IPQ_UART_DM_CMD_RESET_RX, IPQ_UART_DM_CR(base));
+	writel(IPQ_UART_DM_CMD_RESET_TX, IPQ_UART_DM_CR(base));
+	writel(IPQ_UART_DM_CMD_RESET_ERR_STAT,
+		 IPQ_UART_DM_CR(base));
+	writel(IPQ_UART_DM_CMD_RES_TX_ERR, IPQ_UART_DM_CR(base));
+	writel(IPQ_UART_DM_CMD_RES_STALE_INT, IPQ_UART_DM_CR(base));
+
+	return IPQ_UART_DM_E_SUCCESS;
+}
+
+/*
+ * msm_boot_uart_dm_init - initilaizes UART controller
+ * @uart_dm_base: UART controller base address
+ */
+static unsigned int msm_boot_uart_dm_init(void  *uart_dm_base)
+{
+	/* Configure UART mode registers MR1 and MR2 */
+	/* Hardware flow control isn't supported */
+	writel(0x0, IPQ_UART_DM_MR1(uart_dm_base));
+
+	/* 8-N-1 configuration: 8 data bits - No parity - 1 stop bit */
+	writel(IPQ_UART_DM_8_N_1_MODE,
+		 IPQ_UART_DM_MR2(uart_dm_base));
+
+	/* Configure Interrupt Mask register IMR */
+	writel(IPQ_UART_DM_IMR_ENABLED,
+		 IPQ_UART_DM_IMR(uart_dm_base));
+
+	/*
+	 * Configure Tx and Rx watermarks configuration registers
+	 * TX watermark value is set to 0 - interrupt is generated when
+	 * FIFO level is less than or equal to 0
+	 */
+	writel(IPQ_UART_DM_TFW_VALUE,
+		 IPQ_UART_DM_TFWR(uart_dm_base));
+
+	/* RX watermark value */
+	writel(IPQ_UART_DM_RFW_VALUE,
+		 IPQ_UART_DM_RFWR(uart_dm_base));
+
+	/* Configure Interrupt Programming Register */
+	/* Set initial Stale timeout value */
+	writel(IPQ_UART_DM_STALE_TIMEOUT_LSB,
+		IPQ_UART_DM_IPR(uart_dm_base));
+
+	/* Configure IRDA if required */
+	/* Disabling IRDA mode */
+	writel(0x0, IPQ_UART_DM_IRDA(uart_dm_base));
+
+	/* Configure hunt character value in HCR register */
+	/* Keep it in reset state */
+	writel(0x0, IPQ_UART_DM_HCR(uart_dm_base));
+
+	/*
+	 * Configure Rx FIFO base address
+	 * Both TX/RX shares same SRAM and default is half-n-half.
+	 * Sticking with default value now.
+	 * As such RAM size is (2^RAM_ADDR_WIDTH, 32-bit entries).
+	 * We have found RAM_ADDR_WIDTH = 0x7f
+	 */
+
+	/* Issue soft reset command */
+	msm_boot_uart_dm_reset(uart_dm_base);
+
+	/* Enable/Disable Rx/Tx DM interfaces */
+	/* Data Mover not currently utilized. */
+	writel(0, IPQ_UART_DM_DMEN(uart_dm_base));
+
+	/* Enable transmitter */
+	writel(IPQ_UART_DM_CR_TX_ENABLE,
+		IPQ_UART_DM_CR(uart_dm_base));
+
+	/* Initialize Receive Path */
+	msm_boot_uart_dm_init_rx_transfer(uart_dm_base);
+
+	return 0;
+}
+
+/**
+ * serial_havechar - checks if data available for reading
+ *
+ * Returns 1 if data available, 0 otherwise
+ */
+int serial_havechar(void)
+{
+	/* Return if data is already read */
+	if (uart_ready_data_count)
+		return 1;
+
+	/* Read data from the FIFO */
+	if (msm_boot_uart_dm_read() != IPQ_UART_DM_E_SUCCESS)
+		return 0;
+
+	return 1;
+}
+
+/**
+ * ipq806x_serial_getc - reads a character
+ *
+ * Returns the character read from serial port.
+ */
+int serial_getchar(void)
+{
+	uint8_t byte;
+
+	while (!serial_havechar()) {
+		/* wait for incoming data */
+	}
+
+	byte = (uint8_t)(uart_rx_fifo_word & 0xff);
+	uart_rx_fifo_word = uart_rx_fifo_word >> 8;
+	uart_ready_data_count--;
+
+	return byte;
+}
+
+/* For simplicity sake let's rely on coreboot initalizing the UART. */
+void serial_console_init(void)
+{
+	struct cb_serial *sc_ptr = lib_sysinfo.serial;
+
+	if (!sc_ptr)
+		return;
+
+	base_uart_addr = (void *) sc_ptr->baseaddr;
+
+	consin.havekey = serial_havechar;
+	consin.getchar = serial_getchar;
+
+	consout.putchar = serial_putchar;
+
+	console_add_output_driver(&consout);
+	console_add_input_driver(&consin);
+}