drivers: dcc: Support JTAG DCC console

The legacy console is gone. Re-add DCC console support based
on the multi-console framework.

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Change-Id: Ia8388721093bc1be3af40974530d7c9a9ae5f43e

docs/about/maintainers.rst

@@ -142,6 +142,15 @@ eMMC/UFS drivers
 :|F|: include/drivers/ufs.h
 :|F|: include/drivers/synopsys/dw_mmc.h
 
+JTAG DCC console driver
+^^^^^^^^^^^^^^^^^^^^^^^
+:M: Michal Simek <michal.simek@xilinx.com>
+:G: `michalsimek`_
+:M: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@xilinx.com>
+:G: `venkatesh`_
+:F: drivers/arm/dcc/
+:F: include/drivers/arm/dcc.h
+
 Power State Coordination Interface (PSCI)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 :|M|: Javier Almansa Sobrino <Javier.AlmansaSobrino@arm.com>

drivers/arm/dcc/dcc_console.c

@@ -0,0 +1,152 @@
+/*
+ * Copyright (c) 2015-2021, Xilinx Inc.
+ * Written by Michal Simek.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <stddef.h>
+#include <arch_helpers.h>
+#include <drivers/arm/dcc.h>
+#include <drivers/console.h>
+#include <drivers/delay_timer.h>
+#include <lib/mmio.h>
+
+/* DCC Status Bits */
+#define DCC_STATUS_RX		BIT(30)
+#define DCC_STATUS_TX		BIT(29)
+#define TIMEOUT_COUNT_US	U(0x10624)
+
+struct dcc_console {
+	struct console console;
+};
+
+static inline uint32_t __dcc_getstatus(void)
+{
+	return read_mdccsr_el0();
+}
+
+static inline char __dcc_getchar(void)
+{
+	char c;
+
+	c = read_dbgdtrrx_el0();
+
+	return c;
+}
+
+static inline void __dcc_putchar(char c)
+{
+	/*
+	 * The typecast is to make absolutely certain that 'c' is
+	 * zero-extended.
+	 */
+	write_dbgdtrtx_el0((unsigned char)c);
+}
+
+static int32_t dcc_status_timeout(uint32_t mask)
+{
+	const unsigned int timeout_count = TIMEOUT_COUNT_US;
+	uint64_t timeout;
+	unsigned int status;
+
+	timeout = timeout_init_us(timeout_count);
+
+	do {
+		status = (__dcc_getstatus() & mask);
+		if (timeout_elapsed(timeout)) {
+			return -ETIMEDOUT;
+		}
+	} while ((status != 0U));
+
+	return 0;
+}
+
+static int32_t dcc_console_putc(int32_t ch, struct console *console)
+{
+	unsigned int status;
+
+	status = dcc_status_timeout(DCC_STATUS_TX);
+	if (status != 0U) {
+		return status;
+	}
+	__dcc_putchar(ch);
+
+	return ch;
+}
+
+static int32_t dcc_console_getc(struct console *console)
+{
+	unsigned int status;
+
+	status = dcc_status_timeout(DCC_STATUS_RX);
+	if (status != 0U) {
+		return status;
+	}
+
+	return __dcc_getchar();
+}
+
+int32_t dcc_console_init(unsigned long base_addr, uint32_t uart_clk,
+		      uint32_t baud_rate)
+{
+	return 0; /* No init needed */
+}
+
+/**
+ * dcc_console_flush() - Function to force a write of all buffered data
+ *		          that hasn't been output.
+ * @console		Console struct
+ *
+ */
+static void dcc_console_flush(struct console *console)
+{
+	unsigned int status;
+
+	status = dcc_status_timeout(DCC_STATUS_TX);
+	if (status != 0U) {
+		return;
+	}
+}
+
+static struct dcc_console dcc_console = {
+	.console = {
+		.flags = CONSOLE_FLAG_BOOT |
+			CONSOLE_FLAG_RUNTIME,
+		.putc = dcc_console_putc,
+		.getc = dcc_console_getc,
+		.flush = dcc_console_flush,
+	},
+};
+
+int console_dcc_register(void)
+{
+	return console_register(&dcc_console.console);
+}

include/arch/aarch64/arch_helpers.h

@@ -260,6 +260,9 @@ DEFINE_SYSREG_RW_FUNCS(spsr_el3)
 DEFINE_SYSREG_RW_FUNCS(elr_el1)
 DEFINE_SYSREG_RW_FUNCS(elr_el2)
 DEFINE_SYSREG_RW_FUNCS(elr_el3)
+DEFINE_SYSREG_RW_FUNCS(mdccsr_el0)
+DEFINE_SYSREG_RW_FUNCS(dbgdtrrx_el0)
+DEFINE_SYSREG_RW_FUNCS(dbgdtrtx_el0)
 
 DEFINE_SYSOP_FUNC(wfi)
 DEFINE_SYSOP_FUNC(wfe)

include/drivers/arm/dcc.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2021,  Xilinx Inc.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef DCC_H
+#define DCC_H
+
+#include <stdint.h>
+#include <drivers/console.h>
+
+/*
+ * Initialize a new dcc console instance and register it with the console
+ * framework.
+ */
+int console_dcc_register(void);
+
+#endif /* DCC */