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Commit 43f1831b authored by Karthikeyan Ramasubramanian's avatar Karthikeyan Ramasubramanian Committed by Greg Kroah-Hartman
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tty: serial: qcom_geni_serial: Add early console support 



Add early console support in Qualcomm Technologies Inc., GENI based
UART controller.

Signed-off-by: default avatarKarthikeyan Ramasubramanian <kramasub@codeaurora.org>
Signed-off-by: default avatarGirish Mahadevan <girishm@codeaurora.org>
Reviewed-by: default avatarStephen Boyd <swboyd@chromium.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ec91df8d

Documentation/admin-guide/kernel-parameters.txt

+6 −0
Original line number Diff line number Diff line
@@ -1025,6 +1025,12 @@ 
			address. The serial port must already be setup

			and configured. Options are not yet supported.



		qcom_geni,<addr>

			Start an early, polled-mode console on a Qualcomm

			Generic Interface (GENI) based serial port at the

			specified address. The serial port must already be

			setup and configured. Options are not yet supported.



	earlyprintk=	[X86,SH,ARM,M68k,S390]

			earlyprintk=vga

			earlyprintk=efi

drivers/tty/serial/qcom_geni_serial.c

+72 −2
Original line number Diff line number Diff line
@@ -196,8 +196,19 @@ static bool qcom_geni_serial_poll_bit(struct uart_port *uport, 
		timeout_us = ((fifo_bits * USEC_PER_SEC) / baud) + 500;

	}



	return !readl_poll_timeout_atomic(uport->membase + offset, reg,

			 (bool)(reg & field) == set, 10, timeout_us);

	/*

	 * Use custom implementation instead of readl_poll_atomic since ktimer

	 * is not ready at the time of early console.

	 */

	timeout_us = DIV_ROUND_UP(timeout_us, 10) * 10;

	while (timeout_us) {

		reg = readl_relaxed(uport->membase + offset);

		if ((bool)(reg & field) == set)

			return true;

		udelay(10);

		timeout_us -= 10;

	}

	return false;

}



static void qcom_geni_serial_setup_tx(struct uart_port *uport, u32 xmit_size)
@@ -943,6 +954,65 @@ static int __init qcom_geni_console_setup(struct console *co, char *options) 
	return uart_set_options(uport, co, baud, parity, bits, flow);

}



static void qcom_geni_serial_earlycon_write(struct console *con,

					const char *s, unsigned int n)

{

	struct earlycon_device *dev = con->data;



	__qcom_geni_serial_console_write(&dev->port, s, n);

}



static int __init qcom_geni_serial_earlycon_setup(struct earlycon_device *dev,

								const char *opt)

{

	struct uart_port *uport = &dev->port;

	u32 tx_trans_cfg;

	u32 tx_parity_cfg = 0;	/* Disable Tx Parity */

	u32 rx_trans_cfg = 0;

	u32 rx_parity_cfg = 0;	/* Disable Rx Parity */

	u32 stop_bit_len = 0;	/* Default stop bit length - 1 bit */

	u32 bits_per_char;

	struct geni_se se;



	if (!uport->membase)

		return -EINVAL;



	memset(&se, 0, sizeof(se));

	se.base = uport->membase;

	if (geni_se_read_proto(&se) != GENI_SE_UART)

		return -ENXIO;

	/*

	 * Ignore Flow control.

	 * n = 8.

	 */

	tx_trans_cfg = UART_CTS_MASK;

	bits_per_char = BITS_PER_BYTE;



	/*

	 * Make an unconditional cancel on the main sequencer to reset

	 * it else we could end up in data loss scenarios.

	 */

	qcom_geni_serial_poll_tx_done(uport);

	qcom_geni_serial_abort_rx(uport);

	geni_se_config_packing(&se, BITS_PER_BYTE, 1, false, true, false);

	geni_se_init(&se, DEF_FIFO_DEPTH_WORDS / 2, DEF_FIFO_DEPTH_WORDS - 2);

	geni_se_select_mode(&se, GENI_SE_FIFO);



	writel_relaxed(tx_trans_cfg, uport->membase + SE_UART_TX_TRANS_CFG);

	writel_relaxed(tx_parity_cfg, uport->membase + SE_UART_TX_PARITY_CFG);

	writel_relaxed(rx_trans_cfg, uport->membase + SE_UART_RX_TRANS_CFG);

	writel_relaxed(rx_parity_cfg, uport->membase + SE_UART_RX_PARITY_CFG);

	writel_relaxed(bits_per_char, uport->membase + SE_UART_TX_WORD_LEN);

	writel_relaxed(bits_per_char, uport->membase + SE_UART_RX_WORD_LEN);

	writel_relaxed(stop_bit_len, uport->membase + SE_UART_TX_STOP_BIT_LEN);



	dev->con->write = qcom_geni_serial_earlycon_write;

	dev->con->setup = NULL;

	return 0;

}

OF_EARLYCON_DECLARE(qcom_geni, "qcom,geni-debug-uart",

				qcom_geni_serial_earlycon_setup);



static int __init console_register(struct uart_driver *drv)

{

	return uart_register_driver(drv);