diff options
Diffstat (limited to 'sys/arch')
| -rw-r--r-- | sys/arch/amd64/isa/mc1468.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/sys/arch/amd64/isa/mc1468.c b/sys/arch/amd64/isa/mc1468.c new file mode 100644 index 0000000..f1421a4 --- /dev/null +++ b/sys/arch/amd64/isa/mc1468.c @@ -0,0 +1,200 @@ +/* + * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. 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. + * 3. Neither the name of Hyra 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 OWNER 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 <sys/types.h> +#include <sys/param.h> +#include <sys/time.h> +#include <sys/driver.h> +#include <sys/device.h> +#include <sys/syslog.h> +#include <fs/devfs.h> +#include <machine/pio.h> +#include <machine/cdefs.h> +#include <string.h> + +#define MC1468_REGSEL 0x70 +#define MC1468_DATA 0x71 + +/* Register A flags */ +#define MC1468_UPDATING BIT(7) + +/* Register B flags */ +#define MC1468_DAYSAVE BIT(1) +#define MC1468_CLOCK24 BIT(2) + +static struct cdevsw mc1468_cdevsw; + +/* + * Read a byte from an MC1468XX register. + */ +static uint8_t +mc1468_read(uint8_t reg) +{ + outb(MC1468_REGSEL, reg); + return inb(MC1468_DATA); +} + +/* + * Returns true if the MC1468XX is updating + * its time registers. + */ +static bool +mc1468_updating(void) +{ + uint8_t reg_b; + + reg_b = mc1468_read(0xB); + return ISSET(reg_b, MC1468_UPDATING) != 0; +} + +/* + * Check if date `a' and date `b' are synced. + * Used to make sure a bogus date caused by a + * read right before an MC1468XX register + * update doesn't occur. + */ +static bool +mc1468_date_synced(struct date *a, struct date *b) +{ + if (a->sec != b->sec) + return false; + if (a->min != b->min) + return false; + if (a->hour != b->hour) + return false; + + return true; +} + +/* + * Sometimes the clock chip may encode the + * date in binary-coded-decimal. This function + * converts a date in BCD format to plain binary. + */ +static void +mc1468_bcd_conv(struct date *dp) +{ + dp->sec = (dp->sec & 0x0F) + ((dp->sec / 16) * 10); + dp->min = (dp->min & 0x0F) + ((dp->min / 16) * 10); + dp->hour = (dp->hour & 0x0F) + (((dp->hour & 0x70) / 16) * 10); + dp->hour |= dp->hour & 0x80; +} + +/* + * Read the time for the clock without syncing + * it up. + * + * XXX: Please use mc1468_get_date() instead as + * this function may return inconsistent + * values if not used correctly. + */ +static void +__mc1468_get_time(struct date *dp) +{ + dp->sec = mc1468_read(0x00); + dp->min = mc1468_read(0x02); + dp->hour = mc1468_read(0x04); +} + +static int +mc1468_get_date(struct date *dp) +{ + struct date date_cur, date_last; + uint8_t reg_b = mc1468_read(0x0B); + + while (mc1468_updating()) { + __mc1468_get_time(&date_last); + } + + /* + * Get the current date and time. + * + * XXX: The date and time returned by __mc1468_get_time() + * may at times be out of sync, read it twice to + * make sure everything is synced up. + */ + do { + while (mc1468_updating()) { + md_pause(); + } + __mc1468_get_time(&date_last); + date_cur.sec = date_last.sec; + date_cur.min = date_last.min; + date_cur.hour = date_last.hour; + } while (!mc1468_date_synced(&date_cur, &date_last)); + + /* Is this in BCD? */ + if (!ISSET(reg_b, 0x04)) { + mc1468_bcd_conv(&date_cur); + } + + /* 24-hour mode? */ + if (ISSET(reg_b, MC1468_CLOCK24)) { + date_cur.hour = ((date_cur.hour & 0x7F) + 12) % 24; + } + + *dp = date_cur; + return 0; +} + +static int +mc1468_dev_read(dev_t dev, struct sio_txn *sio, int flags) +{ + struct date d; + size_t len = sizeof(d); + + if (sio->len > len) { + sio->len = len; + } + + mc1468_get_date(&d); + memcpy(sio->buf, &d, sio->len); + return sio->len; +} + +static int +mc1468_init(void) +{ + char devname[] = "rtc"; + devmajor_t major; + dev_t dev; + + major = dev_alloc_major(); + dev = dev_alloc(major); + dev_register(major, dev, &mc1468_cdevsw); + devfs_create_entry(devname, major, dev, 0444); + return 0; +} + +static struct cdevsw mc1468_cdevsw = { + .read = mc1468_dev_read, + .write = nowrite +}; + +DRIVER_EXPORT(mc1468_init); |