Add early console support in Qualcomm Technologies Inc., GENI based UART controller. Signed-off-by: Karthikeyan Ramasubramanian <kramasub@xxxxxxxxxxxxxx> Signed-off-by: Girish Mahadevan <girishm@xxxxxxxxxxxxxx> --- Documentation/admin-guide/kernel-parameters.txt | 6 ++ drivers/tty/serial/qcom_geni_serial.c | 74 ++++++++++++++++++++++++- 2 files changed, 78 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 11fc28e..1dda0b6 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -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 diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index c8fd7cd..9d773a9 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -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); -- Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html