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
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