GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

source/bootloader/u-boot-2020.01/drivers/serial/serial_bcm283x_mu.c

@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org>
+ *
+ * Derived from pl01x code:
+ *
+ * (C) Copyright 2000
+ * Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
+ *
+ * (C) Copyright 2004
+ * ARM Ltd.
+ * Philippe Robin, <philippe.robin@arm.com>
+ */
+
+/* Simple U-Boot driver for the BCM283x mini UART */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <watchdog.h>
+#include <asm/gpio.h>
+#include <asm/io.h>
+#include <serial.h>
+#include <dm/platform_data/serial_bcm283x_mu.h>
+#include <dm/pinctrl.h>
+#include <linux/compiler.h>
+
+struct bcm283x_mu_regs {
+	u32 io;
+	u32 iir;
+	u32 ier;
+	u32 lcr;
+	u32 mcr;
+	u32 lsr;
+	u32 msr;
+	u32 scratch;
+	u32 cntl;
+	u32 stat;
+	u32 baud;
+};
+
+#define BCM283X_MU_LCR_DATA_SIZE_8	3
+
+#define BCM283X_MU_LSR_TX_IDLE		BIT(6)
+/* This actually means not full, but is named not empty in the docs */
+#define BCM283X_MU_LSR_TX_EMPTY		BIT(5)
+#define BCM283X_MU_LSR_RX_READY		BIT(0)
+
+struct bcm283x_mu_priv {
+	struct bcm283x_mu_regs *regs;
+};
+
+static int bcm283x_mu_serial_getc(struct udevice *dev);
+
+static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
+{
+	struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
+	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
+	struct bcm283x_mu_regs *regs = priv->regs;
+	u32 divider;
+
+	if (plat->skip_init)
+		goto out;
+
+	divider = plat->clock / (baudrate * 8);
+
+	writel(BCM283X_MU_LCR_DATA_SIZE_8, &regs->lcr);
+	writel(divider - 1, &regs->baud);
+
+out:
+	/* Flush the RX queue - all data in there is bogus */
+	while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ;
+
+	return 0;
+}
+
+static int bcm283x_mu_serial_probe(struct udevice *dev)
+{
+	struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
+	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
+
+	priv->regs = (struct bcm283x_mu_regs *)plat->base;
+
+	return 0;
+}
+
+static int bcm283x_mu_serial_getc(struct udevice *dev)
+{
+	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
+	struct bcm283x_mu_regs *regs = priv->regs;
+	u32 data;
+
+	/* Wait until there is data in the FIFO */
+	if (!(readl(&regs->lsr) & BCM283X_MU_LSR_RX_READY))
+		return -EAGAIN;
+
+	data = readl(&regs->io);
+
+	return (int)data;
+}
+
+static int bcm283x_mu_serial_putc(struct udevice *dev, const char data)
+{
+	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
+	struct bcm283x_mu_regs *regs = priv->regs;
+
+	/* Wait until there is space in the FIFO */
+	if (!(readl(&regs->lsr) & BCM283X_MU_LSR_TX_EMPTY))
+		return -EAGAIN;
+
+	/* Send the character */
+	writel(data, &regs->io);
+
+	return 0;
+}
+
+static int bcm283x_mu_serial_pending(struct udevice *dev, bool input)
+{
+	struct bcm283x_mu_priv *priv = dev_get_priv(dev);
+	struct bcm283x_mu_regs *regs = priv->regs;
+	unsigned int lsr;
+
+	lsr = readl(&regs->lsr);
+
+	if (input) {
+		WATCHDOG_RESET();
+		return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0;
+	} else {
+		return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1;
+	}
+}
+
+static const struct dm_serial_ops bcm283x_mu_serial_ops = {
+	.putc = bcm283x_mu_serial_putc,
+	.pending = bcm283x_mu_serial_pending,
+	.getc = bcm283x_mu_serial_getc,
+	.setbrg = bcm283x_mu_serial_setbrg,
+};
+
+#if CONFIG_IS_ENABLED(OF_CONTROL)
+static const struct udevice_id bcm283x_mu_serial_id[] = {
+	{.compatible = "brcm,bcm2835-aux-uart"},
+	{}
+};
+
+/*
+ * Check if this serial device is muxed
+ *
+ * The serial device will only work properly if it has been muxed to the serial
+ * pins by firmware. Check whether that happened here.
+ *
+ * @return true if serial device is muxed, false if not
+ */
+static bool bcm283x_is_serial_muxed(void)
+{
+	int serial_gpio = 15;
+	struct udevice *dev;
+
+	if (uclass_first_device(UCLASS_PINCTRL, &dev) || !dev)
+		return false;
+
+	if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT5)
+		return false;
+
+	return true;
+}
+
+static int bcm283x_mu_serial_ofdata_to_platdata(struct udevice *dev)
+{
+	struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
+	fdt_addr_t addr;
+
+	/* Don't spawn the device if it's not muxed */
+	if (!bcm283x_is_serial_muxed())
+		return -ENODEV;
+
+	addr = devfdt_get_addr(dev);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	plat->base = addr;
+	plat->clock = dev_read_u32_default(dev, "clock", 1);
+
+	/*
+	 * TODO: Reinitialization doesn't always work for now, just skip
+	 *       init always - we know we're already initialized
+	 */
+	plat->skip_init = true;
+
+	return 0;
+}
+#endif
+
+U_BOOT_DRIVER(serial_bcm283x_mu) = {
+	.name = "serial_bcm283x_mu",
+	.id = UCLASS_SERIAL,
+	.of_match = of_match_ptr(bcm283x_mu_serial_id),
+	.ofdata_to_platdata = of_match_ptr(bcm283x_mu_serial_ofdata_to_platdata),
+	.platdata_auto_alloc_size = sizeof(struct bcm283x_mu_serial_platdata),
+	.probe = bcm283x_mu_serial_probe,
+	.ops = &bcm283x_mu_serial_ops,
+#if !CONFIG_IS_ENABLED(OF_CONTROL) || CONFIG_IS_ENABLED(OF_BOARD)
+	.flags = DM_FLAG_PRE_RELOC,
+#endif
+	.priv_auto_alloc_size = sizeof(struct bcm283x_mu_priv),
+};