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-rw-r--r--drivers/rtc/rtc-gamecube.c378
1 files changed, 378 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-gamecube.c b/drivers/rtc/rtc-gamecube.c
new file mode 100644
index 000000000..c828bc8e0
--- /dev/null
+++ b/drivers/rtc/rtc-gamecube.c
@@ -0,0 +1,378 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nintendo GameCube, Wii and Wii U RTC driver
+ *
+ * This driver is for the MX23L4005, more specifically its real-time clock and
+ * SRAM storage. The value returned by the RTC counter must be added with the
+ * offset stored in a bias register in SRAM (on the GameCube and Wii) or in
+ * /config/rtc.xml (on the Wii U). The latter being very impractical to access
+ * from Linux, this driver assumes the bootloader has read it and stored it in
+ * SRAM like for the other two consoles.
+ *
+ * This device sits on a bus named EXI (which is similar to SPI), channel 0,
+ * device 1. This driver assumes no other user of the EXI bus, which is
+ * currently the case but would have to be reworked to add support for other
+ * GameCube hardware exposed on this bus.
+ *
+ * References:
+ * - https://wiiubrew.org/wiki/Hardware/RTC
+ * - https://wiibrew.org/wiki/MX23L4005
+ *
+ * Copyright (C) 2018 rw-r-r-0644
+ * Copyright (C) 2021 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
+ *
+ * Based on rtc-gcn.c
+ * Copyright (C) 2004-2009 The GameCube Linux Team
+ * Copyright (C) 2005,2008,2009 Albert Herranz
+ * Based on gamecube_time.c from Torben Nielsen.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+#include <linux/time.h>
+
+/* EXI registers */
+#define EXICSR 0
+#define EXICR 12
+#define EXIDATA 16
+
+/* EXI register values */
+#define EXICSR_DEV 0x380
+ #define EXICSR_DEV1 0x100
+#define EXICSR_CLK 0x070
+ #define EXICSR_CLK_1MHZ 0x000
+ #define EXICSR_CLK_2MHZ 0x010
+ #define EXICSR_CLK_4MHZ 0x020
+ #define EXICSR_CLK_8MHZ 0x030
+ #define EXICSR_CLK_16MHZ 0x040
+ #define EXICSR_CLK_32MHZ 0x050
+#define EXICSR_INT 0x008
+ #define EXICSR_INTSET 0x008
+
+#define EXICR_TSTART 0x001
+#define EXICR_TRSMODE 0x002
+ #define EXICR_TRSMODE_IMM 0x000
+#define EXICR_TRSTYPE 0x00C
+ #define EXICR_TRSTYPE_R 0x000
+ #define EXICR_TRSTYPE_W 0x004
+#define EXICR_TLEN 0x030
+ #define EXICR_TLEN32 0x030
+
+/* EXI registers values to access the RTC */
+#define RTC_EXICSR (EXICSR_DEV1 | EXICSR_CLK_8MHZ | EXICSR_INTSET)
+#define RTC_EXICR_W (EXICR_TSTART | EXICR_TRSMODE_IMM | EXICR_TRSTYPE_W | EXICR_TLEN32)
+#define RTC_EXICR_R (EXICR_TSTART | EXICR_TRSMODE_IMM | EXICR_TRSTYPE_R | EXICR_TLEN32)
+#define RTC_EXIDATA_W 0x80000000
+
+/* RTC registers */
+#define RTC_COUNTER 0x200000
+#define RTC_SRAM 0x200001
+#define RTC_SRAM_BIAS 0x200004
+#define RTC_SNAPSHOT 0x204000
+#define RTC_ONTMR 0x210000
+#define RTC_OFFTMR 0x210001
+#define RTC_TEST0 0x210004
+#define RTC_TEST1 0x210005
+#define RTC_TEST2 0x210006
+#define RTC_TEST3 0x210007
+#define RTC_CONTROL0 0x21000c
+#define RTC_CONTROL1 0x21000d
+
+/* RTC flags */
+#define RTC_CONTROL0_UNSTABLE_POWER 0x00000800
+#define RTC_CONTROL0_LOW_BATTERY 0x00000200
+
+struct priv {
+ struct regmap *regmap;
+ void __iomem *iob;
+ u32 rtc_bias;
+};
+
+static int exi_read(void *context, u32 reg, u32 *data)
+{
+ struct priv *d = (struct priv *)context;
+ void __iomem *iob = d->iob;
+
+ /* The spin loops here loop about 15~16 times each, so there is no need
+ * to use a more expensive sleep method.
+ */
+
+ /* Write register offset */
+ iowrite32be(RTC_EXICSR, iob + EXICSR);
+ iowrite32be(reg << 8, iob + EXIDATA);
+ iowrite32be(RTC_EXICR_W, iob + EXICR);
+ while (!(ioread32be(iob + EXICSR) & EXICSR_INTSET))
+ cpu_relax();
+
+ /* Read data */
+ iowrite32be(RTC_EXICSR, iob + EXICSR);
+ iowrite32be(RTC_EXICR_R, iob + EXICR);
+ while (!(ioread32be(iob + EXICSR) & EXICSR_INTSET))
+ cpu_relax();
+ *data = ioread32be(iob + EXIDATA);
+
+ /* Clear channel parameters */
+ iowrite32be(0, iob + EXICSR);
+
+ return 0;
+}
+
+static int exi_write(void *context, u32 reg, u32 data)
+{
+ struct priv *d = (struct priv *)context;
+ void __iomem *iob = d->iob;
+
+ /* The spin loops here loop about 15~16 times each, so there is no need
+ * to use a more expensive sleep method.
+ */
+
+ /* Write register offset */
+ iowrite32be(RTC_EXICSR, iob + EXICSR);
+ iowrite32be(RTC_EXIDATA_W | (reg << 8), iob + EXIDATA);
+ iowrite32be(RTC_EXICR_W, iob + EXICR);
+ while (!(ioread32be(iob + EXICSR) & EXICSR_INTSET))
+ cpu_relax();
+
+ /* Write data */
+ iowrite32be(RTC_EXICSR, iob + EXICSR);
+ iowrite32be(data, iob + EXIDATA);
+ iowrite32be(RTC_EXICR_W, iob + EXICR);
+ while (!(ioread32be(iob + EXICSR) & EXICSR_INTSET))
+ cpu_relax();
+
+ /* Clear channel parameters */
+ iowrite32be(0, iob + EXICSR);
+
+ return 0;
+}
+
+static const struct regmap_bus exi_bus = {
+ /* TODO: is that true? Not that it matters here, but still. */
+ .fast_io = true,
+ .reg_read = exi_read,
+ .reg_write = exi_write,
+};
+
+static int gamecube_rtc_read_time(struct device *dev, struct rtc_time *t)
+{
+ struct priv *d = dev_get_drvdata(dev);
+ int ret;
+ u32 counter;
+ time64_t timestamp;
+
+ ret = regmap_read(d->regmap, RTC_COUNTER, &counter);
+ if (ret)
+ return ret;
+
+ /* Add the counter and the bias to obtain the timestamp */
+ timestamp = (time64_t)d->rtc_bias + counter;
+ rtc_time64_to_tm(timestamp, t);
+
+ return 0;
+}
+
+static int gamecube_rtc_set_time(struct device *dev, struct rtc_time *t)
+{
+ struct priv *d = dev_get_drvdata(dev);
+ time64_t timestamp;
+
+ /* Subtract the timestamp and the bias to obtain the counter value */
+ timestamp = rtc_tm_to_time64(t);
+ return regmap_write(d->regmap, RTC_COUNTER, timestamp - d->rtc_bias);
+}
+
+static int gamecube_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+ struct priv *d = dev_get_drvdata(dev);
+ int value;
+ int control0;
+ int ret;
+
+ switch (cmd) {
+ case RTC_VL_READ:
+ ret = regmap_read(d->regmap, RTC_CONTROL0, &control0);
+ if (ret)
+ return ret;
+
+ value = 0;
+ if (control0 & RTC_CONTROL0_UNSTABLE_POWER)
+ value |= RTC_VL_DATA_INVALID;
+ if (control0 & RTC_CONTROL0_LOW_BATTERY)
+ value |= RTC_VL_BACKUP_LOW;
+ return put_user(value, (unsigned int __user *)arg);
+
+ default:
+ return -ENOIOCTLCMD;
+ }
+}
+
+static const struct rtc_class_ops gamecube_rtc_ops = {
+ .read_time = gamecube_rtc_read_time,
+ .set_time = gamecube_rtc_set_time,
+ .ioctl = gamecube_rtc_ioctl,
+};
+
+static int gamecube_rtc_read_offset_from_sram(struct priv *d)
+{
+ struct device_node *np;
+ int ret;
+ struct resource res;
+ void __iomem *hw_srnprot;
+ u32 old;
+
+ np = of_find_compatible_node(NULL, NULL, "nintendo,latte-srnprot");
+ if (!np)
+ np = of_find_compatible_node(NULL, NULL,
+ "nintendo,hollywood-srnprot");
+ if (!np) {
+ pr_info("HW_SRNPROT not found, assuming a GameCube\n");
+ return regmap_read(d->regmap, RTC_SRAM_BIAS, &d->rtc_bias);
+ }
+
+ ret = of_address_to_resource(np, 0, &res);
+ of_node_put(np);
+ if (ret) {
+ pr_err("no io memory range found\n");
+ return -1;
+ }
+
+ hw_srnprot = ioremap(res.start, resource_size(&res));
+ old = ioread32be(hw_srnprot);
+
+ /* TODO: figure out why we use this magic constant. I obtained it by
+ * reading the leftover value after boot, after IOSU already ran.
+ *
+ * On my Wii U, setting this register to 1 prevents the console from
+ * rebooting properly, so wiiubrew.org must be missing something.
+ *
+ * See https://wiiubrew.org/wiki/Hardware/Latte_registers
+ */
+ if (old != 0x7bf)
+ iowrite32be(0x7bf, hw_srnprot);
+
+ /* Get the offset from RTC SRAM.
+ *
+ * Its default location on the GameCube and on the Wii is in the SRAM,
+ * while on the Wii U the bootloader needs to fill it with the contents
+ * of /config/rtc.xml on the SLC (the eMMC). We don’t do that from
+ * Linux since it requires implementing a proprietary filesystem and do
+ * file decryption, instead we require the bootloader to fill the same
+ * SRAM address as on previous consoles.
+ */
+ ret = regmap_read(d->regmap, RTC_SRAM_BIAS, &d->rtc_bias);
+
+ /* Reset SRAM access to how it was before, our job here is done. */
+ if (old != 0x7bf)
+ iowrite32be(old, hw_srnprot);
+
+ iounmap(hw_srnprot);
+
+ if (ret)
+ pr_err("failed to get the RTC bias\n");
+
+ return ret;
+}
+
+static const struct regmap_range rtc_rd_ranges[] = {
+ regmap_reg_range(0x200000, 0x200010),
+ regmap_reg_range(0x204000, 0x204000),
+ regmap_reg_range(0x210000, 0x210001),
+ regmap_reg_range(0x210004, 0x210007),
+ regmap_reg_range(0x21000c, 0x21000d),
+};
+
+static const struct regmap_access_table rtc_rd_regs = {
+ .yes_ranges = rtc_rd_ranges,
+ .n_yes_ranges = ARRAY_SIZE(rtc_rd_ranges),
+};
+
+static const struct regmap_range rtc_wr_ranges[] = {
+ regmap_reg_range(0x200000, 0x200010),
+ regmap_reg_range(0x204000, 0x204000),
+ regmap_reg_range(0x210000, 0x210001),
+ regmap_reg_range(0x21000d, 0x21000d),
+};
+
+static const struct regmap_access_table rtc_wr_regs = {
+ .yes_ranges = rtc_wr_ranges,
+ .n_yes_ranges = ARRAY_SIZE(rtc_wr_ranges),
+};
+
+static const struct regmap_config gamecube_rtc_regmap_config = {
+ .reg_bits = 24,
+ .val_bits = 32,
+ .rd_table = &rtc_rd_regs,
+ .wr_table = &rtc_wr_regs,
+ .max_register = 0x21000d,
+ .name = "gamecube-rtc",
+};
+
+static int gamecube_rtc_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct rtc_device *rtc;
+ struct priv *d;
+ int ret;
+
+ d = devm_kzalloc(dev, sizeof(struct priv), GFP_KERNEL);
+ if (!d)
+ return -ENOMEM;
+
+ d->iob = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(d->iob))
+ return PTR_ERR(d->iob);
+
+ d->regmap = devm_regmap_init(dev, &exi_bus, d,
+ &gamecube_rtc_regmap_config);
+ if (IS_ERR(d->regmap))
+ return PTR_ERR(d->regmap);
+
+ ret = gamecube_rtc_read_offset_from_sram(d);
+ if (ret)
+ return ret;
+ dev_dbg(dev, "SRAM bias: 0x%x", d->rtc_bias);
+
+ dev_set_drvdata(dev, d);
+
+ rtc = devm_rtc_allocate_device(dev);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ /* We can represent further than that, but it depends on the stored
+ * bias and we can’t modify it persistently on all supported consoles,
+ * so here we pretend to be limited to 2106.
+ */
+ rtc->range_min = 0;
+ rtc->range_max = U32_MAX;
+ rtc->ops = &gamecube_rtc_ops;
+
+ devm_rtc_register_device(rtc);
+
+ return 0;
+}
+
+static const struct of_device_id gamecube_rtc_of_match[] = {
+ {.compatible = "nintendo,latte-exi" },
+ {.compatible = "nintendo,hollywood-exi" },
+ {.compatible = "nintendo,flipper-exi" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, gamecube_rtc_of_match);
+
+static struct platform_driver gamecube_rtc_driver = {
+ .probe = gamecube_rtc_probe,
+ .driver = {
+ .name = "rtc-gamecube",
+ .of_match_table = gamecube_rtc_of_match,
+ },
+};
+module_platform_driver(gamecube_rtc_driver);
+
+MODULE_AUTHOR("Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>");
+MODULE_DESCRIPTION("Nintendo GameCube, Wii and Wii U RTC driver");
+MODULE_LICENSE("GPL");