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lede/target/linux/silicon/patches-5.19/0148-rtc-Add-new-rtc-macsmc-driver-for-Apple-Silicon-Macs.patch

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From 41fdf7c140ec6b812b2e55a45d9446ba3e60612c Mon Sep 17 00:00:00 2001
From: Hector Martin <marcan@marcan.st>
Date: Tue, 15 Feb 2022 18:47:13 +0900
Subject: [PATCH 148/171] rtc: Add new rtc-macsmc driver for Apple Silicon Macs
Apple Silicon Macs (M1, etc.) have an RTC that is part of the PMU IC,
but most of the PMU functionality is abstracted out by the SMC.
On T600x machines, the RTC counter must be accessed via the SMC to
get full functionality, and it seems likely that future machines
will move towards making SMC handle all RTC functionality.
The SMC RTC counter access is implemented on all current machines
as of the time of this writing, on firmware 12.x. However, the RTC
offset (needed to set the time) is still only accessible via direct
PMU access. To handle this, we expose the RTC offset as an NVMEM
cell from the SPMI PMU device node, and this driver consumes that
cell and uses it to compute/set the current time.
Alarm functionality is not yet implemented. This would also go via
the PMU today, but could change in the future.
Signed-off-by: Hector Martin <marcan@marcan.st>
---
drivers/rtc/Kconfig | 13 ++++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-macsmc.c | 130 +++++++++++++++++++++++++++++++++++++++
3 files changed, 144 insertions(+)
create mode 100644 drivers/rtc/rtc-macsmc.c
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index a00f901b5c1d..8717f2d9381c 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1973,4 +1973,17 @@ config RTC_DRV_MSC313
This driver can also be built as a module, if so, the module
will be called "rtc-msc313".
+config RTC_DRV_MACSMC
+ tristate "Apple Mac SMC RTC"
+ depends on ARCH_APPLE || COMPILE_TEST
+ depends on APPLE_SMC
+ depends on OF
+ default ARCH_APPLE
+ help
+ If you say yes here you get support for RTC functions
+ inside Apple SPMI PMUs.
+
+ To compile this driver as a module, choose M here: the
+ module will be called rtc-macsmc.
+
endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index fb04467b652d..68519801a320 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -89,6 +89,7 @@ obj-$(CONFIG_RTC_DRV_M41T94) += rtc-m41t94.o
obj-$(CONFIG_RTC_DRV_M48T35) += rtc-m48t35.o
obj-$(CONFIG_RTC_DRV_M48T59) += rtc-m48t59.o
obj-$(CONFIG_RTC_DRV_M48T86) += rtc-m48t86.o
+obj-$(CONFIG_RTC_DRV_MACSMC) += rtc-macsmc.o
obj-$(CONFIG_RTC_DRV_MAX6900) += rtc-max6900.o
obj-$(CONFIG_RTC_DRV_MAX6902) += rtc-max6902.o
obj-$(CONFIG_RTC_DRV_MAX6916) += rtc-max6916.o
diff --git a/drivers/rtc/rtc-macsmc.c b/drivers/rtc/rtc-macsmc.c
new file mode 100644
index 000000000000..34730c925248
--- /dev/null
+++ b/drivers/rtc/rtc-macsmc.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SMC RTC driver
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/bitops.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/macsmc.h>
+#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+/* 48-bit RTC */
+#define RTC_BYTES 6
+#define RTC_BITS (8 * RTC_BYTES)
+
+/* 32768 Hz clock */
+#define RTC_SEC_SHIFT 15
+
+struct macsmc_rtc {
+ struct device *dev;
+ struct apple_smc *smc;
+ struct rtc_device *rtc_dev;
+ struct nvmem_cell *rtc_offset;
+};
+
+static int macsmc_rtc_get_time(struct device *dev, struct rtc_time *tm)
+{
+ struct macsmc_rtc *rtc = dev_get_drvdata(dev);
+ u64 ctr = 0, off = 0;
+ time64_t now;
+ void *p_off;
+ size_t len;
+ int ret;
+
+ ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES);
+ if (ret != RTC_BYTES)
+ return ret < 0 ? ret : -EIO;
+
+ p_off = nvmem_cell_read(rtc->rtc_offset, &len);
+ if (IS_ERR(p_off))
+ return PTR_ERR(p_off);
+ if (len < RTC_BYTES) {
+ kfree(p_off);
+ return -EIO;
+ }
+
+ memcpy(&off, p_off, RTC_BYTES);
+ kfree(p_off);
+
+ /* Sign extend from 48 to 64 bits, then arithmetic shift right 15 bits to get seconds */
+ now = sign_extend64(ctr + off, RTC_BITS - 1) >> RTC_SEC_SHIFT;
+ rtc_time64_to_tm(now, tm);
+
+ return ret;
+}
+
+static int macsmc_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct macsmc_rtc *rtc = dev_get_drvdata(dev);
+ u64 ctr = 0, off = 0;
+ int ret;
+
+ ret = apple_smc_read(rtc->smc, SMC_KEY(CLKM), &ctr, RTC_BYTES);
+ if (ret != RTC_BYTES)
+ return ret < 0 ? ret : -EIO;
+
+ /* This sets the offset such that the set second begins now */
+ off = (rtc_tm_to_time64(tm) << RTC_SEC_SHIFT) - ctr;
+ return nvmem_cell_write(rtc->rtc_offset, &off, RTC_BYTES);
+}
+
+static const struct rtc_class_ops macsmc_rtc_ops = {
+ .read_time = macsmc_rtc_get_time,
+ .set_time = macsmc_rtc_set_time,
+};
+
+static int macsmc_rtc_probe(struct platform_device *pdev)
+{
+ struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
+ struct macsmc_rtc *rtc;
+
+ /* Ignore devices without this functionality */
+ if (!apple_smc_key_exists(smc, SMC_KEY(CLKM)))
+ return -ENODEV;
+
+ rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+ if (!rtc)
+ return -ENOMEM;
+
+ rtc->dev = &pdev->dev;
+ rtc->smc = smc;
+
+ pdev->dev.of_node = of_get_child_by_name(pdev->dev.parent->of_node, "rtc");
+
+ rtc->rtc_offset = devm_nvmem_cell_get(&pdev->dev, "rtc_offset");
+ if (IS_ERR(rtc->rtc_offset))
+ return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_offset),
+ "Failed to get rtc_offset NVMEM cell\n");
+
+ rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(rtc->rtc_dev))
+ return PTR_ERR(rtc->rtc_dev);
+
+ rtc->rtc_dev->ops = &macsmc_rtc_ops;
+ rtc->rtc_dev->range_min = S64_MIN >> (RTC_SEC_SHIFT + (64 - RTC_BITS));
+ rtc->rtc_dev->range_max = S64_MAX >> (RTC_SEC_SHIFT + (64 - RTC_BITS));
+
+ platform_set_drvdata(pdev, rtc);
+
+ return devm_rtc_register_device(rtc->rtc_dev);
+}
+
+static struct platform_driver macsmc_rtc_driver = {
+ .driver = {
+ .name = "macsmc-rtc",
+ .owner = THIS_MODULE,
+ },
+ .probe = macsmc_rtc_probe,
+};
+module_platform_driver(macsmc_rtc_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Apple SMC RTC driver");
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_ALIAS("platform:macsmc-rtc");
--
2.34.1
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