rtc: add rtc command

Mostly as an aid for debugging RTC drivers, provide a command that can
be used to read/write arbitrary registers (assuming the driver
provides the read/write methods or their single-register-at-a-time
variants).

Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>

cmd/Kconfig

@@ -1739,6 +1739,12 @@ config CMD_DATE
 	  Enable the 'date' command for getting/setting the time/date in RTC
 	  devices.
 
+config CMD_RTC
+	bool "rtc"
+	depends on DM_RTC
+	help
+	  Enable the 'rtc' command for low-level access to RTC devices.
+
 config CMD_TIME
 	bool "time"
 	help

cmd/Makefile

@@ -122,6 +122,7 @@ obj-$(CONFIG_CMD_REISER) += reiser.o
 obj-$(CONFIG_CMD_REMOTEPROC) += remoteproc.o
 obj-$(CONFIG_CMD_RNG) += rng.o
 obj-$(CONFIG_CMD_ROCKUSB) += rockusb.o
+obj-$(CONFIG_CMD_RTC) += rtc.o
 obj-$(CONFIG_SANDBOX) += host.o
 obj-$(CONFIG_CMD_SATA) += sata.o
 obj-$(CONFIG_CMD_NVME) += nvme.o

cmd/rtc.c

@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <common.h>
+#include <command.h>
+#include <dm.h>
+#include <hexdump.h>
+#include <i2c.h>
+#include <mapmem.h>
+#include <rtc.h>
+
+#define MAX_RTC_BYTES 32
+
+static int do_rtc_read(struct udevice *dev, int argc, char * const argv[])
+{
+	u8 buf[MAX_RTC_BYTES];
+	int reg, len, ret, r;
+
+	if (argc < 2 || argc > 3)
+		return CMD_RET_USAGE;
+
+	reg = simple_strtoul(argv[0], NULL, 16);
+	len = simple_strtoul(argv[1], NULL, 16);
+
+	if (argc == 3) {
+		u8 *addr;
+
+		addr = map_sysmem(simple_strtoul(argv[2], NULL, 16), len);
+		ret = dm_rtc_read(dev, reg, addr, len);
+		unmap_sysmem(addr);
+		if (ret) {
+			printf("dm_rtc_read() failed: %d\n", ret);
+			return CMD_RET_FAILURE;
+		}
+		return CMD_RET_SUCCESS;
+	}
+
+	while (len) {
+		r = min_t(int, len, sizeof(buf));
+		ret = dm_rtc_read(dev, reg, buf, r);
+		if (ret) {
+			printf("dm_rtc_read() failed: %d\n", ret);
+			return CMD_RET_FAILURE;
+		}
+		print_buffer(reg, buf, 1, r, 0);
+		len -= r;
+		reg += r;
+	}
+
+	return CMD_RET_SUCCESS;
+}
+
+static int do_rtc_write(struct udevice *dev, int argc, char * const argv[])
+{
+	u8 buf[MAX_RTC_BYTES];
+	int reg, len, ret;
+	const char *s;
+	int slen;
+
+	if (argc < 2 || argc > 3)
+		return CMD_RET_USAGE;
+
+	reg = simple_strtoul(argv[0], NULL, 16);
+
+	if (argc == 3) {
+		u8 *addr;
+
+		len = simple_strtoul(argv[1], NULL, 16);
+		addr = map_sysmem(simple_strtoul(argv[2], NULL, 16), len);
+		ret = dm_rtc_write(dev, reg, addr, len);
+		unmap_sysmem(addr);
+		if (ret) {
+			printf("dm_rtc_write() failed: %d\n", ret);
+			return CMD_RET_FAILURE;
+		}
+		return CMD_RET_SUCCESS;
+	}
+
+	s = argv[1];
+	slen = strlen(s);
+
+	if (slen % 2) {
+		printf("invalid hex string\n");
+		return CMD_RET_FAILURE;
+	}
+
+	while (slen) {
+		len = min_t(int, slen / 2, sizeof(buf));
+		if (hex2bin(buf, s, len)) {
+			printf("invalid hex string\n");
+			return CMD_RET_FAILURE;
+		}
+
+		ret = dm_rtc_write(dev, reg, buf, len);
+		if (ret) {
+			printf("dm_rtc_write() failed: %d\n", ret);
+			return CMD_RET_FAILURE;
+		}
+		s += 2 * len;
+		slen -= 2 * len;
+	}
+
+	return CMD_RET_SUCCESS;
+}
+
+int do_rtc(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[])
+{
+	static int curr_rtc;
+	struct udevice *dev;
+	int ret, idx;
+
+	if (argc < 2)
+		return CMD_RET_USAGE;
+
+	argc--;
+	argv++;
+
+	if (!strcmp(argv[0], "list")) {
+		struct uclass *uc;
+
+		idx = 0;
+		uclass_id_foreach_dev(UCLASS_RTC, dev, uc) {
+			printf("RTC #%d - %s\n", idx++, dev->name);
+		}
+		if (!idx) {
+			printf("*** no RTC devices available ***\n");
+			return CMD_RET_FAILURE;
+		}
+		return CMD_RET_SUCCESS;
+	}
+
+	idx = curr_rtc;
+	if (!strcmp(argv[0], "dev") && argc >= 2)
+		idx = simple_strtoul(argv[1], NULL, 10);
+
+	ret = uclass_get_device(UCLASS_RTC, idx, &dev);
+	if (ret) {
+		printf("Cannot find RTC #%d: err=%d\n", idx, ret);
+		return CMD_RET_FAILURE;
+	}
+
+	if (!strcmp(argv[0], "dev")) {
+		/* Show the existing or newly selected RTC */
+		if (argc >= 2)
+			curr_rtc = idx;
+		printf("RTC #%d - %s\n", idx, dev->name);
+		return CMD_RET_SUCCESS;
+	}
+
+	if (!strcmp(argv[0], "read"))
+		return do_rtc_read(dev, argc - 1, argv + 1);
+
+	if (!strcmp(argv[0], "write"))
+		return do_rtc_write(dev, argc - 1, argv + 1);
+
+	return CMD_RET_USAGE;
+}
+
+U_BOOT_CMD(
+	rtc,	5,	0,	do_rtc,
+	"RTC subsystem",
+	"list                        - show available rtc devices\n"
+	"rtc dev [n]                     - show or set current rtc device\n"
+	"rtc read <reg> <count>          - read and display 8-bit registers starting at <reg>\n"
+	"rtc read <reg> <count> <addr>   - read 8-bit registers starting at <reg> to memory <addr>\n"
+	"rtc write <reg> <hexstring>     - write 8-bit registers starting at <reg>\n"
+	"rtc write <reg> <count> <addr>  - write from memory <addr> to 8-bit registers starting at <reg>\n"
+);