Add basic UART drivers

Add basic drivers for:
 - PL011 UART
 - CMSDK APB UART
 - dummy/stub UART

Change-Id: I2f89874fba59044e6c7c084f8e1dc6faa9eb8d1b

7 files changed, 503 insertions, 0 deletions

diff --git a/drivers/CMakeLists.txt b/drivers/CMakeLists.txt
index c130a26..9feeeae 100644
--- a/drivers/CMakeLists.txt
+++ b/drivers/CMakeLists.txt
@@ -18,11 +18,18 @@
 
 add_library(ethosu_drivers INTERFACE)
 
+#############################################################################
 # Mailbox driver
+#############################################################################
 add_subdirectory(mailbox)
 target_link_libraries(ethosu_drivers INTERFACE ethosu_mailbox)
 
+#############################################################################
 # MHU drivers
+#############################################################################
+# NOTE: These are all built and linked from a CMake perspective. However the
+#       application code can instantiate one or more of the drivers. The
+#       one(s) not used will later be removed by the linker.
 add_subdirectory(mhu_v2)
 add_subdirectory(mhu_juno)
 add_subdirectory(mhu_dummy)
@@ -30,3 +37,9 @@ target_link_libraries(ethosu_drivers INTERFACE ethosu_mhu_v2)
 target_link_libraries(ethosu_drivers INTERFACE ethosu_mhu_juno)
 target_link_libraries(ethosu_drivers INTERFACE ethosu_mhu_dummy)
 
+#############################################################################
+# UART drivers
+#############################################################################
+# NOTE: All UART drivers are built, however a platform application should
+#       link the appropriate driver target (see drivers/uart/CMakeLists.txt).
+add_subdirectory(uart)
diff --git a/drivers/uart/CMakeLists.txt b/drivers/uart/CMakeLists.txt
new file mode 100644
index 0000000..1293bdc
--- /dev/null
+++ b/drivers/uart/CMakeLists.txt
@@ -0,0 +1,41 @@
+#
+# Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the License); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an AS IS BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+add_library(ethosu_uart_common INTERFACE)
+
+target_include_directories(ethosu_uart_common INTERFACE
+                           include
+                           ${CMAKE_CURRENT_BINARY_DIR})
+
+# UART configuration (can be overriden from user project)
+set(UART0_BASE        "0xFFFFFFFF" CACHE STRING "UART base address")
+set(UART0_BAUDRATE    "115200"     CACHE STRING "UART baudrate")
+set(SYSTEM_CORE_CLOCK "25000000"   CACHE STRING "System core clock (Hz)")
+
+# Generate UART configuration file
+configure_file("${CMAKE_CURRENT_SOURCE_DIR}/uart_config.h.in" "${CMAKE_CURRENT_BINARY_DIR}/uart_config.h")
+
+# Drivers
+add_library(ethosu_uart_cmsdk_apb STATIC src/uart_cmsdk_apb.c)
+target_link_libraries(ethosu_uart_cmsdk_apb PUBLIC ethosu_uart_common)
+
+add_library(ethosu_uart_pl011 STATIC src/uart_pl011.c)
+target_link_libraries(ethosu_uart_pl011 PUBLIC ethosu_uart_common)
+
+add_library(ethosu_uart_dummy STATIC src/uart_dummy.c)
+target_link_libraries(ethosu_uart_dummy PUBLIC ethosu_uart_common)
diff --git a/drivers/uart/include/uart_stdout.h b/drivers/uart/include/uart_stdout.h
new file mode 100644
index 0000000..02f8e49
--- /dev/null
+++ b/drivers/uart/include/uart_stdout.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _UART_STDOUT_H_
+#define _UART_STDOUT_H_
+
+#if __cplusplus
+extern "C" {
+#endif
+
+void UartStdOutInit(void);
+unsigned char UartPutc(unsigned char my_ch);
+unsigned char UartGetc(void);
+unsigned int GetLine(char *lp, unsigned int len);
+
+#if __cplusplus
+}
+#endif
+
+#endif
diff --git a/drivers/uart/src/uart_cmsdk_apb.c b/drivers/uart/src/uart_cmsdk_apb.c
new file mode 100644
index 0000000..2639ef5
--- /dev/null
+++ b/drivers/uart/src/uart_cmsdk_apb.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Basic CMSDK APB UART driver */
+
+#include "uart_config.h"
+#include "uart_stdout.h"
+#include <stdint.h>
+#include <stdio.h>
+
+#define CNTLQ     0x11
+#define CNTLS     0x13
+#define DEL       0x7F
+#define BACKSPACE 0x08
+#define CR        0x0D
+#define LF        0x0A
+#define ESC       0x1B
+
+#define __IO volatile
+#define __I  volatile const
+#define __O  volatile
+
+typedef struct {
+    __IO uint32_t DATA;  /* Offset: 0x000 (R/W) Data Register    */
+    __IO uint32_t STATE; /* Offset: 0x004 (R/W) Status Register  */
+    __IO uint32_t CTRL;  /* Offset: 0x008 (R/W) Control Register */
+    union {
+        __I uint32_t INTSTATUS; /* Offset: 0x00C (R/ ) Interrupt Status Register */
+        __O uint32_t INTCLEAR;  /* Offset: 0x00C ( /W) Interrupt Clear Register  */
+    };
+    __IO uint32_t BAUDDIV; /* Offset: 0x010 (R/W) Baudrate Divider Register */
+} CMSDK_UART_TypeDef;
+
+#define CMSDK_UART0_BASE     UART0_BASE
+#define CMSDK_UART0          ((CMSDK_UART_TypeDef *)CMSDK_UART0_BASE)
+#define CMSDK_UART0_BAUDRATE UART0_BAUDRATE
+
+void UartStdOutInit(void) {
+    CMSDK_UART0->BAUDDIV = SYSTEM_CORE_CLOCK / CMSDK_UART0_BAUDRATE;
+
+    CMSDK_UART0->CTRL = ((1ul << 0) | /* TX enable */
+                         (1ul << 1)); /* RX enable */
+}
+
+// Output a character
+unsigned char UartPutc(unsigned char my_ch) {
+    while ((CMSDK_UART0->STATE & 1))
+        ; // Wait if Transmit Holding register is full
+
+    if (my_ch == '\n') {
+        CMSDK_UART0->DATA = '\r';
+        while ((CMSDK_UART0->STATE & 1))
+            ; // Wait if Transmit Holding register is full
+    }
+
+    CMSDK_UART0->DATA = my_ch; // write to transmit holding register
+
+    return (my_ch);
+}
+
+// Get a character
+unsigned char UartGetc(void) {
+    unsigned char my_ch;
+    // unsigned int  cnt;
+
+    while ((CMSDK_UART0->STATE & 2) == 0) // Wait if Receive Holding register is empty
+        ;
+
+    my_ch = CMSDK_UART0->DATA;
+
+    // Convert CR to LF
+    if (my_ch == '\r')
+        my_ch = '\n';
+
+    return (my_ch);
+}
+
+// Get line from terminal
+unsigned int GetLine(char *lp, unsigned int len) {
+    unsigned int cnt = 0;
+    char c;
+
+    do {
+        c = UartGetc();
+        switch (c) {
+        case CNTLQ: /* ignore Control S/Q             */
+        case CNTLS:
+            break;
+        case BACKSPACE:
+        case DEL:
+            if (cnt == 0) {
+                break;
+            }
+            cnt--;          /* decrement count                */
+            lp--;           /* and line pointer               */
+            UartPutc(0x08); /* echo backspace                 */
+            UartPutc(' ');
+            UartPutc(0x08);
+            fflush(stdout);
+            break;
+        case ESC:
+        case 0:
+            *lp = 0; /* ESC - stop editing line        */
+            return 0;
+        case CR: /* CR - done, stop editing line   */
+            *lp = c;
+            lp++;  /* increment line pointer         */
+            cnt++; /* and count                      */
+            c = LF;
+        default:
+            UartPutc(*lp = c); /* echo and store character       */
+            fflush(stdout);
+            lp++;  /* increment line pointer         */
+            cnt++; /* and count                      */
+            break;
+        }
+    } while (cnt < len - 2 && c != LF); /* check limit and CR             */
+    *lp = 0;                            /* mark end of string             */
+    return 1;
+}
diff --git a/drivers/uart/src/uart_dummy.c b/drivers/uart/src/uart_dummy.c
new file mode 100644
index 0000000..ebe384b
--- /dev/null
+++ b/drivers/uart/src/uart_dummy.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "uart_stdout.h"
+
+void UartStdOutInit(void) {}
+
+unsigned char UartPutc(unsigned char c) {
+    (void)c;
+    return 0;
+}
+
+unsigned char UartGetc(void) {
+    return 0;
+}
+
+unsigned int GetLine(char *lp, unsigned int len) {
+    (void)lp;
+    (void)len;
+    return 0;
+}
diff --git a/drivers/uart/src/uart_pl011.c b/drivers/uart/src/uart_pl011.c
new file mode 100644
index 0000000..617ce5f
--- /dev/null
+++ b/drivers/uart/src/uart_pl011.c
@@ -0,0 +1,220 @@
+/*
+ * Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Basic PL011 UART driver */
+
+#include "uart_config.h"
+#include "uart_stdout.h"
+#include <stdint.h>
+#include <stdio.h>
+
+#define CNTLQ     0x11
+#define CNTLS     0x13
+#define DEL       0x7F
+#define BACKSPACE 0x08
+#define CR        0x0D
+#define LF        0x0A
+#define ESC       0x1B
+
+/*****************************************************************************/
+/*  UART Control Register Locations                                          */
+/*****************************************************************************/
+#define UART0_DR   *((volatile uint32_t *)UART0_BASE)
+#define UART0_RSR  *((volatile uint32_t *)(UART0_BASE + 0x04))
+#define UART0_ECR  *((volatile uint32_t *)(UART0_BASE + 0x04))
+#define UART0_LCRH *((volatile uint32_t *)(UART0_BASE + 0x2C))
+#define UART0_LCRM *((volatile uint32_t *)(UART0_BASE + 0x28))
+#define UART0_LCRL *((volatile uint32_t *)(UART0_BASE + 0x24))
+#define UART0_CR   *((volatile uint32_t *)(UART0_BASE + 0x30))
+#define UART0_FR   *((volatile uint32_t *)(UART0_BASE + 0x18))
+#define UART0_IIR  *((volatile uint32_t *)(UART0_BASE + 0x1C))
+#define UART0_ICR  *((volatile uint32_t *)(UART0_BASE + 0x44))
+
+/*****************************************************************************/
+/* Received Status Register - RSR                                            */
+/*****************************************************************************/
+#define RSR_OVERRUN_ERROR 0x08
+#define RSR_BREAK_ERROR   0x04
+#define RSR_PARITY_ERROR  0x02
+#define RSR_FRAMING_ERROR 0x01
+
+/*****************************************************************************/
+/* Line Control High Byte Register - LCRH                                    */
+/*****************************************************************************/
+#define LCRH_WORD_LENGTH_8 0x60
+#define LCRH_WORD_LENGTH_7 0x40
+#define LCRH_WORD_LENGTH_6 0x20
+#define LCRH_WORD_LENGTH_5 0x00
+#define LCRH_FIFO_ENABLED  0x10
+#define LCRH_2_STOP_BITS   0x08
+#define LCRH_EVEN_PARITY   0x04
+#define LCRH_PARITY_ENABLE 0x02
+#define LCRH_SEND_BREAK    0x01
+
+/*****************************************************************************/
+/* Line Control Medium Byte Register - LCRM                                  */
+/* This register specifies the high byte of the Baud rate divisor            */
+/*****************************************************************************/
+#define LCRM_BAUD_460800 0x00
+#define LCRM_BAUD_230400 0x00
+#define LCRM_BAUD_115200 0x00
+#define LCRM_BAUD_76800  0x00
+#define LCRM_BAUD_57600  0x00
+#define LCRM_BAUD_38400  0x00
+#define LCRM_BAUD_19200  0x00
+#define LCRM_BAUD_14400  0x00
+#define LCRM_BAUD_9600   0x00
+#define LCRM_BAUD_2400   0x01
+#define LCRM_BAUD_1200   0x02
+
+/*****************************************************************************/
+/* Line Control Low Byte Register - LCRL                                     */
+/* This register specifies the low byte of the Baud rate divisor             */
+/*****************************************************************************/
+#define LCRL_BAUD_460800 0x01
+#define LCRL_BAUD_230400 0x03
+#define LCRL_BAUD_115200 0x07
+#define LCRL_BAUD_76800  0x0B
+#define LCRL_BAUD_57600  0x0F
+#define LCRL_BAUD_38400  0xC
+#define LCRL_BAUD_19200  0x2F
+#define LCRL_BAUD_14400  0x3F
+#define LCRL_BAUD_9600   0x5F
+#define LCRL_BAUD_2400   0x7F
+#define LCRL_BAUD_1200   0xFF
+
+/*****************************************************************************/
+/* Control Register - CR                                                     */
+/*****************************************************************************/
+#define CR_LOOP_BACK_EN   0x80
+#define CR_TIMEOUT_INT_EN 0x40
+#define CR_TX_INT_ENABLE  0x100
+#define CR_RX_INT_ENABLE  0x200
+#define CR_MODSTAT_INT_EN 0x08
+#define CR_UART_ENABLE    0x01
+
+/*****************************************************************************/
+/* Flag Register - FR                                                        */
+/*****************************************************************************/
+#define FR_TX_FIFO_EMPTY  0x80
+#define FR_RX_FIFO_FULL   0x40
+#define FR_TX_FIFO_FULL   0x20
+#define FR_RX_FIFO_EMPTY  0x10
+#define FR_BUSY           0x08
+#define FR_CARRIER_DETECT 0x04
+#define FR_SET_READY      0x02
+#define FR_CLEAR_TO_SEND  0x01
+
+/*****************************************************************************/
+/* Interrupt Identification Register - IIR                                   */
+/*****************************************************************************/
+#define IIR_RX_TIME_OUT 0x08
+#define IIR_TX          0x04
+#define IIR_RX          0x02
+#define IIR_MODEM       0x01
+
+void UartStdOutInit(void) {
+    // Disable the serial port while setting the baud rate and word length
+    UART0_CR = 0;
+
+    // Clear the receive status register
+    UART0_ECR = 0;
+
+    // Set the correct baud rate and word length
+    UART0_LCRL = LCRL_BAUD_115200;
+    UART0_LCRM = LCRM_BAUD_115200;
+    UART0_LCRH = LCRH_WORD_LENGTH_8;
+
+    // Explicitly disable FIFO's for char mode
+    UART0_LCRH &= ~LCRH_FIFO_ENABLED;
+
+    // Enable UART0 (and RX/TX) without interrupts
+    UART0_CR = CR_UART_ENABLE | CR_TX_INT_ENABLE | CR_RX_INT_ENABLE;
+}
+
+unsigned char UartPutc(unsigned char ch) {
+    if (ch == '\n') {
+        (void)UartPutc('\r');
+    }
+    while (UART0_FR & FR_TX_FIFO_FULL)
+        ;
+    UART0_DR = ch;
+
+    return ch;
+}
+
+unsigned char UartGetc(void) {
+    unsigned char c;
+    while (UART0_FR & FR_RX_FIFO_EMPTY)
+        ;
+    c = UART0_DR;
+    if (c == '\r') {
+        c = '\n';
+    }
+
+    return c;
+}
+
+// Get line from terminal
+unsigned int GetLine(char *lp, unsigned int len) {
+    unsigned int cnt = 0;
+    char c;
+
+    do {
+        c = UartGetc();
+        switch (c) {
+        case CNTLQ: /* ignore Control S/Q             */
+        case CNTLS:
+            break;
+        case BACKSPACE:
+        case DEL:
+            if (cnt == 0) {
+                break;
+            }
+            cnt--;          /* decrement count                */
+            lp--;           /* and line pointer               */
+            UartPutc(0x08); /* echo backspace                 */
+            UartPutc(' ');
+            UartPutc(0x08);
+            fflush(stdout);
+            break;
+        case ESC:
+        case 0:
+            *lp = 0; /* ESC - stop editing line        */
+            return 0;
+        case CR: /* CR - done, stop editing line   */
+            *lp = c;
+            lp++;  /* increment line pointer         */
+            cnt++; /* and count                      */
+            c = LF;
+            UartPutc(*lp = c); /* echo and store character       */
+            fflush(stdout);
+            lp++;  /* increment line pointer         */
+            cnt++; /* and count                      */
+            break;
+        default:
+            UartPutc(*lp = c); /* echo and store character       */
+            fflush(stdout);
+            lp++;  /* increment line pointer         */
+            cnt++; /* and count                      */
+            break;
+        }
+    } while (cnt < len - 2 && c != LF); /* check limit and CR             */
+    *lp = 0;                            /* mark end of string             */
+    return 1;
+}
diff --git a/drivers/uart/uart_config.h.in b/drivers/uart/uart_config.h.in
new file mode 100644
index 0000000..eb858fa
--- /dev/null
+++ b/drivers/uart/uart_config.h.in
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2019-2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#define UART0_BASE          (@UART0_BASE@)
+#define UART0_BAUDRATE      (@UART0_BAUDRATE@)
+#define SYSTEM_CORE_CLOCK   (@SYSTEM_CORE_CLOCK@)