diff options
Diffstat (limited to 'drivers/rtc/rtc-ssd202d.c')
| -rw-r--r-- | drivers/rtc/rtc-ssd202d.c | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ssd202d.c b/drivers/rtc/rtc-ssd202d.c new file mode 100644 index 000000000000..ed6493260096 --- /dev/null +++ b/drivers/rtc/rtc-ssd202d.c @@ -0,0 +1,249 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Real time clocks driver for MStar/SigmaStar SSD202D SoCs. + * + * (C) 2021 Daniel Palmer + * (C) 2023 Romain Perier + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/platform_device.h> +#include <linux/rtc.h> +#include <linux/regmap.h> +#include <linux/pm.h> + +#define REG_CTRL 0x0 +#define REG_CTRL1 0x4 +#define REG_ISO_CTRL 0xc +#define REG_WRDATA_L 0x10 +#define REG_WRDATA_H 0x14 +#define REG_ISOACK 0x20 +#define REG_RDDATA_L 0x24 +#define REG_RDDATA_H 0x28 +#define REG_RDCNT_L 0x30 +#define REG_RDCNT_H 0x34 +#define REG_CNT_TRIG 0x38 +#define REG_PWRCTRL 0x3c +#define REG_RTC_TEST 0x54 + +#define CNT_RD_TRIG_BIT BIT(0) +#define CNT_RD_BIT BIT(0) +#define BASE_WR_BIT BIT(1) +#define BASE_RD_BIT BIT(2) +#define CNT_RST_BIT BIT(3) +#define ISO_CTRL_ACK_MASK BIT(3) +#define ISO_CTRL_ACK_SHIFT 3 +#define SW0_WR_BIT BIT(5) +#define SW1_WR_BIT BIT(6) +#define SW0_RD_BIT BIT(7) +#define SW1_RD_BIT BIT(8) + +#define ISO_CTRL_MASK GENMASK(2, 0) + +struct ssd202d_rtc { + struct rtc_device *rtc_dev; + void __iomem *base; +}; + +static u8 read_iso_en(void __iomem *base) +{ + return readb(base + REG_RTC_TEST) & 0x1; +} + +static u8 read_iso_ctrl_ack(void __iomem *base) +{ + return (readb(base + REG_ISOACK) & ISO_CTRL_ACK_MASK) >> ISO_CTRL_ACK_SHIFT; +} + +static int ssd202d_rtc_isoctrl(struct ssd202d_rtc *priv) +{ + static const unsigned int sequence[] = { 0x0, 0x1, 0x3, 0x7, 0x5, 0x1, 0x0 }; + unsigned int val; + struct device *dev = &priv->rtc_dev->dev; + int i, ret; + + /* + * This gates iso_en by writing a special sequence of bytes to iso_ctrl + * and ensuring that it has been correctly applied by reading iso_ctrl_ack + */ + for (i = 0; i < ARRAY_SIZE(sequence); i++) { + writeb(sequence[i] & ISO_CTRL_MASK, priv->base + REG_ISO_CTRL); + + ret = read_poll_timeout(read_iso_ctrl_ack, val, val == (i % 2), 100, + 20 * 100, true, priv->base); + if (ret) { + dev_dbg(dev, "Timeout waiting for ack byte %i (%x) of sequence\n", i, + sequence[i]); + return ret; + } + } + + /* + * At this point iso_en should be raised for 1ms + */ + ret = read_poll_timeout(read_iso_en, val, val, 100, 22 * 100, true, priv->base); + if (ret) + dev_dbg(dev, "Timeout waiting for iso_en\n"); + mdelay(2); + return 0; +} + +static void ssd202d_rtc_read_reg(struct ssd202d_rtc *priv, unsigned int reg, + unsigned int field, unsigned int *base) +{ + unsigned int l, h; + u16 val; + + /* Ask for the content of an RTC value into RDDATA by gating iso_en, + * then iso_en is gated and the content of RDDATA can be read + */ + val = readw(priv->base + reg); + writew(val | field, priv->base + reg); + ssd202d_rtc_isoctrl(priv); + writew(val & ~field, priv->base + reg); + + l = readw(priv->base + REG_RDDATA_L); + h = readw(priv->base + REG_RDDATA_H); + + *base = (h << 16) | l; +} + +static void ssd202d_rtc_write_reg(struct ssd202d_rtc *priv, unsigned int reg, + unsigned int field, u32 base) +{ + u16 val; + + /* Set the content of an RTC value from WRDATA by gating iso_en */ + val = readw(priv->base + reg); + writew(val | field, priv->base + reg); + writew(base, priv->base + REG_WRDATA_L); + writew(base >> 16, priv->base + REG_WRDATA_H); + ssd202d_rtc_isoctrl(priv); + writew(val & ~field, priv->base + reg); +} + +static int ssd202d_rtc_read_counter(struct ssd202d_rtc *priv, unsigned int *counter) +{ + unsigned int l, h; + u16 val; + + val = readw(priv->base + REG_CTRL1); + writew(val | CNT_RD_BIT, priv->base + REG_CTRL1); + ssd202d_rtc_isoctrl(priv); + writew(val & ~CNT_RD_BIT, priv->base + REG_CTRL1); + + val = readw(priv->base + REG_CTRL1); + writew(val | CNT_RD_TRIG_BIT, priv->base + REG_CNT_TRIG); + writew(val & ~CNT_RD_TRIG_BIT, priv->base + REG_CNT_TRIG); + + l = readw(priv->base + REG_RDCNT_L); + h = readw(priv->base + REG_RDCNT_H); + + *counter = (h << 16) | l; + + return 0; +} + +static int ssd202d_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct ssd202d_rtc *priv = dev_get_drvdata(dev); + unsigned int sw0, base, counter; + u32 seconds; + int ret; + + /* Check that RTC is enabled by SW */ + ssd202d_rtc_read_reg(priv, REG_CTRL, SW0_RD_BIT, &sw0); + if (sw0 != 1) + return -EINVAL; + + /* Get RTC base value from RDDATA */ + ssd202d_rtc_read_reg(priv, REG_CTRL, BASE_RD_BIT, &base); + /* Get RTC counter value from RDDATA */ + ret = ssd202d_rtc_read_counter(priv, &counter); + if (ret) + return ret; + + seconds = base + counter; + + rtc_time64_to_tm(seconds, tm); + + return 0; +} + +static int ssd202d_rtc_reset_counter(struct ssd202d_rtc *priv) +{ + u16 val; + + val = readw(priv->base + REG_CTRL); + writew(val | CNT_RST_BIT, priv->base + REG_CTRL); + ssd202d_rtc_isoctrl(priv); + writew(val & ~CNT_RST_BIT, priv->base + REG_CTRL); + ssd202d_rtc_isoctrl(priv); + + return 0; +} + +static int ssd202d_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct ssd202d_rtc *priv = dev_get_drvdata(dev); + unsigned long seconds = rtc_tm_to_time64(tm); + + ssd202d_rtc_write_reg(priv, REG_CTRL, BASE_WR_BIT, seconds); + ssd202d_rtc_reset_counter(priv); + ssd202d_rtc_write_reg(priv, REG_CTRL, SW0_WR_BIT, 1); + + return 0; +} + +static const struct rtc_class_ops ssd202d_rtc_ops = { + .read_time = ssd202d_rtc_read_time, + .set_time = ssd202d_rtc_set_time, +}; + +static int ssd202d_rtc_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct ssd202d_rtc *priv; + + priv = devm_kzalloc(&pdev->dev, sizeof(struct ssd202d_rtc), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + priv->rtc_dev = devm_rtc_allocate_device(dev); + if (IS_ERR(priv->rtc_dev)) + return PTR_ERR(priv->rtc_dev); + + priv->rtc_dev->ops = &ssd202d_rtc_ops; + priv->rtc_dev->range_max = U32_MAX; + + platform_set_drvdata(pdev, priv); + + return devm_rtc_register_device(priv->rtc_dev); +} + +static const struct of_device_id ssd202d_rtc_of_match_table[] = { + { .compatible = "mstar,ssd202d-rtc" }, + { } +}; +MODULE_DEVICE_TABLE(of, ssd202d_rtc_of_match_table); + +static struct platform_driver ssd202d_rtc_driver = { + .probe = ssd202d_rtc_probe, + .driver = { + .name = "ssd202d-rtc", + .of_match_table = ssd202d_rtc_of_match_table, + }, +}; +module_platform_driver(ssd202d_rtc_driver); + +MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>"); +MODULE_AUTHOR("Romain Perier <romain.perier@gmail.com>"); +MODULE_DESCRIPTION("MStar SSD202D RTC Driver"); +MODULE_LICENSE("GPL"); |