[U-Boot] [PATCH 1/2] serial: Introduce linflex uart support

[Eddy Petrișor]

From: Stoica Cosmin-Stefan <cosminstefan.stoica at freescale.com>

The Linflex module is integrated on some NXP automotive SoCs part of the former
Freescale portfolio, like S32V234, an SoC for Advanced Driver Assistance
Systems.

Signed-off-by: Stoica Cosmin-Stefan <cosminstefan.stoica at freescale.com>
Signed-off-by: Chircu Bogdan <Bogdan.Chircu at freescale.com>
Signed-off-by: Depons Eric <eric.depons at freescale.com>
Signed-off-by: Eddy Petrișor <eddy.petrisor at gmail.com>
---
 drivers/serial/Makefile             |   1 +
 drivers/serial/serial_linflexuart.c | 147 ++++++++++++++++++++++++++++++++++++
 2 files changed, 148 insertions(+)
 create mode 100644 drivers/serial/serial_linflexuart.c

diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index ee7147a..b009478 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_SCIF_CONSOLE) += serial_sh.o
 obj-$(CONFIG_ZYNQ_SERIAL) += serial_zynq.o
 obj-$(CONFIG_BFIN_SERIAL) += serial_bfin.o
 obj-$(CONFIG_FSL_LPUART) += serial_lpuart.o
+obj-$(CONFIG_FSL_LINFLEXUART) += serial_linflexuart.o
 obj-$(CONFIG_ARC_SERIAL) += serial_arc.o
 obj-$(CONFIG_UNIPHIER_SERIAL) += serial_uniphier.o
 obj-$(CONFIG_STM32_SERIAL) += serial_stm32.o
diff --git a/drivers/serial/serial_linflexuart.c b/drivers/serial/serial_linflexuart.c
new file mode 100644
index 0000000..3c619ce
--- /dev/null
+++ b/drivers/serial/serial_linflexuart.c
@@ -0,0 +1,147 @@
+/*
+ * (C) Copyright 2013-2016 Freescale Semiconductor, Inc.
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <watchdog.h>
+#include <asm/io.h>
+#include <serial.h>
+#include <linux/compiler.h>
+#include <asm/arch/imx-regs.h>
+#include <asm/arch/clock.h>
+
+#define US1_TDRE            (1 << 7)
+#define US1_RDRF            (1 << 5)
+#define UC2_TE              (1 << 3)
+#define LINCR1_INIT         (1 << 0)
+#define LINCR1_MME          (1 << 4)
+#define LINCR1_BF           (1 << 7)
+#define LINSR_LINS_INITMODE (0x00001000)
+#define LINSR_LINS_MASK     (0x0000F000)
+#define UARTCR_UART         (1 << 0)
+#define UARTCR_WL0          (1 << 1)
+#define UARTCR_PCE          (1 << 2)
+#define UARTCR_PC0          (1 << 3)
+#define UARTCR_TXEN         (1 << 4)
+#define UARTCR_RXEN         (1 << 5)
+#define UARTCR_PC1          (1 << 6)
+#define UARTSR_DTF          (1 << 1)
+#define UARTSR_DRF          (1 << 2)
+#define UARTSR_RMB          (1 << 9)
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct linflex_fsl *base = (struct linflex_fsl *)LINFLEXUART_BASE;
+
+static void linflex_serial_setbrg(void)
+{
+	u32 clk = mxc_get_clock(MXC_UART_CLK);
+	u32 ibr, fbr;
+
+	if (!gd->baudrate)
+		gd->baudrate = CONFIG_BAUDRATE;
+
+	ibr = (u32) (clk / (16 * gd->baudrate));
+	fbr = (u32) (clk % (16 * gd->baudrate)) * 16;
+
+	__raw_writel(ibr, &base->linibrr);
+	__raw_writel(fbr, &base->linfbrr);
+}
+
+static int linflex_serial_getc(void)
+{
+	char c;
+
+	/* waiting for data reception complete - TODO: add a timeout */
+	while ((__raw_readb(&base->uartsr) & UARTSR_DRF) != UARTSR_DRF);
+
+	/* waiting for data buffer to be ready - TODO: add a timeout */
+
+	while ((__raw_readl(&base->uartsr) & UARTSR_RMB) != UARTSR_RMB);
+
+	c = __raw_readl(&base->bdrm);
+	__raw_writeb((__raw_readb(&base->uartsr) | (UARTSR_DRF | UARTSR_RMB)),
+		     &base->uartsr);
+	return c;
+}
+
+static void linflex_serial_putc(const char c)
+{
+	if (c == '\n')
+		serial_putc('\r');
+
+	__raw_writeb(c, &base->bdrl);
+
+	/* waiting for data transmission completed - TODO: add a timeout */
+	while ((__raw_readb(&base->uartsr) & UARTSR_DTF) != UARTSR_DTF);
+
+	__raw_writeb((__raw_readb(&base->uartsr) | UARTSR_DTF), &base->uartsr);
+}
+
+/*
+ * Test whether a character is in the RX buffer
+ */
+static int linflex_serial_tstc(void)
+{
+	return 0;
+}
+
+/*
+ * Initialise the serial port with the given baudrate. The settings
+ * are always 8 data bits, no parity, 1 stop bit, no start bits.
+ */
+static int linflex_serial_init(void)
+{
+	volatile u32 ctrl;
+
+	/* set the Linflex in master mode amd activate by-pass filter */
+	ctrl = LINCR1_BF | LINCR1_MME;
+	__raw_writel(ctrl, &base->lincr1);
+
+	/* init mode */
+	ctrl |= LINCR1_INIT;
+	__raw_writel(ctrl, &base->lincr1);
+
+	/* waiting for init mode entry - TODO: add a timeout */
+	while ((__raw_readl(&base->linsr) & LINSR_LINS_MASK) !=
+	       LINSR_LINS_INITMODE);
+
+	/* set UART bit to allow writing other bits */
+	__raw_writel(UARTCR_UART, &base->uartcr);
+
+	/* provide data bits, parity, stop bit, etc */
+	serial_setbrg();
+
+	/* 8 bit data, no parity, Tx and Rx enabled, UART mode */
+	__raw_writel(UARTCR_PC1 | UARTCR_RXEN | UARTCR_TXEN | UARTCR_PC0
+		     | UARTCR_WL0 | UARTCR_UART, &base->uartcr);
+
+	ctrl = __raw_readl(&base->lincr1);
+	ctrl &= ~LINCR1_INIT;
+	__raw_writel(ctrl, &base->lincr1);	/* end init mode */
+
+	return 0;
+}
+
+static struct serial_device linflex_serial_drv = {
+	.name = "linflex_serial",
+	.start = linflex_serial_init,
+	.stop = NULL,
+	.setbrg = linflex_serial_setbrg,
+	.putc = linflex_serial_putc,
+	.puts = default_serial_puts,
+	.getc = linflex_serial_getc,
+	.tstc = linflex_serial_tstc,
+};
+
+void linflex_serial_initialize(void)
+{
+	serial_register(&linflex_serial_drv);
+}
+
+__weak struct serial_device *default_serial_console(void)
+{
+	return &linflex_serial_drv;
+}
-- 
2.1.4