x86: Add Real-Time Clock Driver
This patch adds a driver for Real-Time Clock (RTC). The RTC timer is suitable to implement some operating system features such as the system clock. Actually, the RTC will be used to implement the system clock in galileo platform. The driver introduced by this patch programs the RTC to generate interrupt periodically. The interrupt frequency can be configured by the user. On each RTC interrupt, a callback configured by the user is called. As expected, that callback is executed in interrupt context so the user should be aware of what it is not supposed to do (e.g. to call blocking functions). This patch also adds the inb() helper function to helpers.h. The helpers is a wrapper for assembly 'in' instruction.
This commit is contained in:
Andre Guedes
Jesus Sanchez-Palencia
parent
11098501d8
commit
5f47bafc6a
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@ -1,6 +1,6 @@
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CONTIKI_CPU_DIRS = . drivers
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CONTIKI_SOURCEFILES += mtarch.c gdt.c helpers.S idt.c cpu.c
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CONTIKI_SOURCEFILES += mtarch.c gdt.c helpers.S idt.c cpu.c rtc.c
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### Compiler definitions
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CC = gcc
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92
cpu/x86/drivers/rtc.c
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92
cpu/x86/drivers/rtc.c
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@ -0,0 +1,92 @@
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/*
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* Copyright (C) 2015, Intel Corporation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "drivers/rtc.h"
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#include "helpers.h"
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#include "interrupt.h"
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#define RTC_INDEX_REGISTER 0x70
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#define RTC_TARGET_REGISTER 0x71
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static void (*user_callback)(void);
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static void
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rtc_handler()
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{
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user_callback();
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/* Clear Register C otherwise interrupts will not happen again.
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* Register C is automatically cleared when it is read so we do
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* a dummy read to clear it.
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*/
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outb(RTC_INDEX_REGISTER, 0x0C);
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inb(RTC_TARGET_REGISTER);
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/* Issue the End of Interrupt to PIC */
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outb(0xA0, 0x20);
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outb(0x20, 0x20);
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}
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/*---------------------------------------------------------------------------*/
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/* Initialize the Real Time Clock.
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* @frequency: RTC has very specific values for frequency. They are: 2, 4, 8,
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* 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, and 8192 Hz.
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* value otherwise it will not work properly.
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* @callback: This callback is called every time the RTC IRQ is raised.
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* It is executed in interrupt context.
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*/
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void
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rtc_init(rtc_frequency_t frequency, void (*callback)(void))
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{
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uint8_t reg_a, reg_b;
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user_callback = callback;
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/* FIXME: Once we have a proper API to ask PIC what is the IRQ offset, we
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* should consider using it here.
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*/
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SET_INTERRUPT_HANDLER(40, 0, rtc_handler);
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/* Select interrupt period to 7.8125 ms */
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outb(RTC_INDEX_REGISTER, 0x0A);
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reg_a = inb(RTC_TARGET_REGISTER);
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reg_a &= 0xF0;
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reg_a |= frequency;
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outb(RTC_INDEX_REGISTER, 0x0A);
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outb(RTC_TARGET_REGISTER, reg_a);
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/* Enable periodic interrupt */
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outb(RTC_INDEX_REGISTER, 0x0B);
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reg_b = inb(RTC_TARGET_REGISTER);
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outb(RTC_INDEX_REGISTER, 0x0B);
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outb(RTC_TARGET_REGISTER, reg_b | BIT(6));
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/* Unmask IRQ8 */
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outb(0xA1, 0xFE);
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}
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52
cpu/x86/drivers/rtc.h
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52
cpu/x86/drivers/rtc.h
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@ -0,0 +1,52 @@
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/*
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* Copyright (C) 2015, Intel Corporation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef RTC_H
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#define RTC_H
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typedef enum {
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RTC_8192_HZ = 2,
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RTC_4096_HZ = 3,
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RTC_2048_HZ = 4,
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RTC_1024_HZ = 5,
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RTC_512_HZ = 6,
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RTC_256_HZ = 7,
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RTC_128_HZ = 8,
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RTC_64_HZ = 9,
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RTC_32_HZ = 10,
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RTC_16_HZ = 11,
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RTC_8_HZ = 12,
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RTC_4_HZ = 13,
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RTC_2_HZ = 14,
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} rtc_frequency_t;
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void rtc_init(rtc_frequency_t frequency, void (*callback)(void));
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#endif /* RTC_H */
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@ -42,3 +42,9 @@ outb:
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mov 8(%esp), %al
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out %al, %dx
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ret
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.global inb
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inb:
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mov 4(%esp), %dx
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in %dx, %al
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ret
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@ -43,4 +43,7 @@ void halt(void) __attribute__((__noreturn__));
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*/
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void outb(uint16_t port, uint8_t byte);
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/* Wrapper for the assembly 'in' instruction */
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uint8_t inb(uint16_t port);
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#endif /* HELPERS_H */
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