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- // SPDX-License-Identifier: GPL-2.0
- /*
- * RTC driver for the interal RTC block in the Amlogic Meson6, Meson8,
- * Meson8b and Meson8m2 SoCs.
- *
- * The RTC is split in to two parts, the AHB front end and a simple serial
- * connection to the actual registers. This driver manages both parts.
- *
- * Copyright (c) 2018 Martin Blumenstingl <[email protected]>
- * Copyright (c) 2015 Ben Dooks <[email protected]> for Codethink Ltd
- * Based on origin by Carlo Caione <[email protected]>
- */
- #include <linux/bitfield.h>
- #include <linux/delay.h>
- #include <linux/io.h>
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/nvmem-provider.h>
- #include <linux/of.h>
- #include <linux/platform_device.h>
- #include <linux/regmap.h>
- #include <linux/regulator/consumer.h>
- #include <linux/reset.h>
- #include <linux/rtc.h>
- /* registers accessed from cpu bus */
- #define RTC_ADDR0 0x00
- #define RTC_ADDR0_LINE_SCLK BIT(0)
- #define RTC_ADDR0_LINE_SEN BIT(1)
- #define RTC_ADDR0_LINE_SDI BIT(2)
- #define RTC_ADDR0_START_SER BIT(17)
- #define RTC_ADDR0_WAIT_SER BIT(22)
- #define RTC_ADDR0_DATA GENMASK(31, 24)
- #define RTC_ADDR1 0x04
- #define RTC_ADDR1_SDO BIT(0)
- #define RTC_ADDR1_S_READY BIT(1)
- #define RTC_ADDR2 0x08
- #define RTC_ADDR3 0x0c
- #define RTC_REG4 0x10
- #define RTC_REG4_STATIC_VALUE GENMASK(7, 0)
- /* rtc registers accessed via rtc-serial interface */
- #define RTC_COUNTER (0)
- #define RTC_SEC_ADJ (2)
- #define RTC_REGMEM_0 (4)
- #define RTC_REGMEM_1 (5)
- #define RTC_REGMEM_2 (6)
- #define RTC_REGMEM_3 (7)
- #define RTC_ADDR_BITS (3) /* number of address bits to send */
- #define RTC_DATA_BITS (32) /* number of data bits to tx/rx */
- #define MESON_STATIC_BIAS_CUR (0x5 << 1)
- #define MESON_STATIC_VOLTAGE (0x3 << 11)
- #define MESON_STATIC_DEFAULT (MESON_STATIC_BIAS_CUR | MESON_STATIC_VOLTAGE)
- struct meson_rtc {
- struct rtc_device *rtc; /* rtc device we created */
- struct device *dev; /* device we bound from */
- struct reset_control *reset; /* reset source */
- struct regulator *vdd; /* voltage input */
- struct regmap *peripheral; /* peripheral registers */
- struct regmap *serial; /* serial registers */
- };
- static const struct regmap_config meson_rtc_peripheral_regmap_config = {
- .name = "peripheral-registers",
- .reg_bits = 8,
- .val_bits = 32,
- .reg_stride = 4,
- .max_register = RTC_REG4,
- .fast_io = true,
- };
- /* RTC front-end serialiser controls */
- static void meson_rtc_sclk_pulse(struct meson_rtc *rtc)
- {
- udelay(5);
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SCLK, 0);
- udelay(5);
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SCLK,
- RTC_ADDR0_LINE_SCLK);
- }
- static void meson_rtc_send_bit(struct meson_rtc *rtc, unsigned int bit)
- {
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SDI,
- bit ? RTC_ADDR0_LINE_SDI : 0);
- meson_rtc_sclk_pulse(rtc);
- }
- static void meson_rtc_send_bits(struct meson_rtc *rtc, u32 data,
- unsigned int nr)
- {
- u32 bit = 1 << (nr - 1);
- while (bit) {
- meson_rtc_send_bit(rtc, data & bit);
- bit >>= 1;
- }
- }
- static void meson_rtc_set_dir(struct meson_rtc *rtc, u32 mode)
- {
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SEN, 0);
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SDI, 0);
- meson_rtc_send_bit(rtc, mode);
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SDI, 0);
- }
- static u32 meson_rtc_get_data(struct meson_rtc *rtc)
- {
- u32 tmp, val = 0;
- int bit;
- for (bit = 0; bit < RTC_DATA_BITS; bit++) {
- meson_rtc_sclk_pulse(rtc);
- val <<= 1;
- regmap_read(rtc->peripheral, RTC_ADDR1, &tmp);
- val |= tmp & RTC_ADDR1_SDO;
- }
- return val;
- }
- static int meson_rtc_get_bus(struct meson_rtc *rtc)
- {
- int ret, retries;
- u32 val;
- /* prepare bus for transfers, set all lines low */
- val = RTC_ADDR0_LINE_SDI | RTC_ADDR0_LINE_SEN | RTC_ADDR0_LINE_SCLK;
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, val, 0);
- for (retries = 0; retries < 3; retries++) {
- /* wait for the bus to be ready */
- if (!regmap_read_poll_timeout(rtc->peripheral, RTC_ADDR1, val,
- val & RTC_ADDR1_S_READY, 10,
- 10000))
- return 0;
- dev_warn(rtc->dev, "failed to get bus, resetting RTC\n");
- ret = reset_control_reset(rtc->reset);
- if (ret)
- return ret;
- }
- dev_err(rtc->dev, "bus is not ready\n");
- return -ETIMEDOUT;
- }
- static int meson_rtc_serial_bus_reg_read(void *context, unsigned int reg,
- unsigned int *data)
- {
- struct meson_rtc *rtc = context;
- int ret;
- ret = meson_rtc_get_bus(rtc);
- if (ret)
- return ret;
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SEN,
- RTC_ADDR0_LINE_SEN);
- meson_rtc_send_bits(rtc, reg, RTC_ADDR_BITS);
- meson_rtc_set_dir(rtc, 0);
- *data = meson_rtc_get_data(rtc);
- return 0;
- }
- static int meson_rtc_serial_bus_reg_write(void *context, unsigned int reg,
- unsigned int data)
- {
- struct meson_rtc *rtc = context;
- int ret;
- ret = meson_rtc_get_bus(rtc);
- if (ret)
- return ret;
- regmap_update_bits(rtc->peripheral, RTC_ADDR0, RTC_ADDR0_LINE_SEN,
- RTC_ADDR0_LINE_SEN);
- meson_rtc_send_bits(rtc, data, RTC_DATA_BITS);
- meson_rtc_send_bits(rtc, reg, RTC_ADDR_BITS);
- meson_rtc_set_dir(rtc, 1);
- return 0;
- }
- static const struct regmap_bus meson_rtc_serial_bus = {
- .reg_read = meson_rtc_serial_bus_reg_read,
- .reg_write = meson_rtc_serial_bus_reg_write,
- };
- static const struct regmap_config meson_rtc_serial_regmap_config = {
- .name = "serial-registers",
- .reg_bits = 4,
- .reg_stride = 1,
- .val_bits = 32,
- .max_register = RTC_REGMEM_3,
- .fast_io = false,
- };
- static int meson_rtc_write_static(struct meson_rtc *rtc, u32 data)
- {
- u32 tmp;
- regmap_write(rtc->peripheral, RTC_REG4,
- FIELD_PREP(RTC_REG4_STATIC_VALUE, (data >> 8)));
- /* write the static value and start the auto serializer */
- tmp = FIELD_PREP(RTC_ADDR0_DATA, (data & 0xff)) | RTC_ADDR0_START_SER;
- regmap_update_bits(rtc->peripheral, RTC_ADDR0,
- RTC_ADDR0_DATA | RTC_ADDR0_START_SER, tmp);
- /* wait for the auto serializer to complete */
- return regmap_read_poll_timeout(rtc->peripheral, RTC_REG4, tmp,
- !(tmp & RTC_ADDR0_WAIT_SER), 10,
- 10000);
- }
- /* RTC interface layer functions */
- static int meson_rtc_gettime(struct device *dev, struct rtc_time *tm)
- {
- struct meson_rtc *rtc = dev_get_drvdata(dev);
- u32 time;
- int ret;
- ret = regmap_read(rtc->serial, RTC_COUNTER, &time);
- if (!ret)
- rtc_time64_to_tm(time, tm);
- return ret;
- }
- static int meson_rtc_settime(struct device *dev, struct rtc_time *tm)
- {
- struct meson_rtc *rtc = dev_get_drvdata(dev);
- return regmap_write(rtc->serial, RTC_COUNTER, rtc_tm_to_time64(tm));
- }
- static const struct rtc_class_ops meson_rtc_ops = {
- .read_time = meson_rtc_gettime,
- .set_time = meson_rtc_settime,
- };
- /* NVMEM interface layer functions */
- static int meson_rtc_regmem_read(void *context, unsigned int offset,
- void *buf, size_t bytes)
- {
- struct meson_rtc *rtc = context;
- unsigned int read_offset, read_size;
- read_offset = RTC_REGMEM_0 + (offset / 4);
- read_size = bytes / 4;
- return regmap_bulk_read(rtc->serial, read_offset, buf, read_size);
- }
- static int meson_rtc_regmem_write(void *context, unsigned int offset,
- void *buf, size_t bytes)
- {
- struct meson_rtc *rtc = context;
- unsigned int write_offset, write_size;
- write_offset = RTC_REGMEM_0 + (offset / 4);
- write_size = bytes / 4;
- return regmap_bulk_write(rtc->serial, write_offset, buf, write_size);
- }
- static int meson_rtc_probe(struct platform_device *pdev)
- {
- struct nvmem_config meson_rtc_nvmem_config = {
- .name = "meson-rtc-regmem",
- .type = NVMEM_TYPE_BATTERY_BACKED,
- .word_size = 4,
- .stride = 4,
- .size = 4 * 4,
- .reg_read = meson_rtc_regmem_read,
- .reg_write = meson_rtc_regmem_write,
- };
- struct device *dev = &pdev->dev;
- struct meson_rtc *rtc;
- void __iomem *base;
- int ret;
- u32 tm;
- rtc = devm_kzalloc(dev, sizeof(struct meson_rtc), GFP_KERNEL);
- if (!rtc)
- return -ENOMEM;
- rtc->rtc = devm_rtc_allocate_device(dev);
- if (IS_ERR(rtc->rtc))
- return PTR_ERR(rtc->rtc);
- platform_set_drvdata(pdev, rtc);
- rtc->dev = dev;
- rtc->rtc->ops = &meson_rtc_ops;
- rtc->rtc->range_max = U32_MAX;
- base = devm_platform_ioremap_resource(pdev, 0);
- if (IS_ERR(base))
- return PTR_ERR(base);
- rtc->peripheral = devm_regmap_init_mmio(dev, base,
- &meson_rtc_peripheral_regmap_config);
- if (IS_ERR(rtc->peripheral)) {
- dev_err(dev, "failed to create peripheral regmap\n");
- return PTR_ERR(rtc->peripheral);
- }
- rtc->reset = devm_reset_control_get(dev, NULL);
- if (IS_ERR(rtc->reset)) {
- dev_err(dev, "missing reset line\n");
- return PTR_ERR(rtc->reset);
- }
- rtc->vdd = devm_regulator_get(dev, "vdd");
- if (IS_ERR(rtc->vdd)) {
- dev_err(dev, "failed to get the vdd-supply\n");
- return PTR_ERR(rtc->vdd);
- }
- ret = regulator_enable(rtc->vdd);
- if (ret) {
- dev_err(dev, "failed to enable vdd-supply\n");
- return ret;
- }
- ret = meson_rtc_write_static(rtc, MESON_STATIC_DEFAULT);
- if (ret) {
- dev_err(dev, "failed to set static values\n");
- goto out_disable_vdd;
- }
- rtc->serial = devm_regmap_init(dev, &meson_rtc_serial_bus, rtc,
- &meson_rtc_serial_regmap_config);
- if (IS_ERR(rtc->serial)) {
- dev_err(dev, "failed to create serial regmap\n");
- ret = PTR_ERR(rtc->serial);
- goto out_disable_vdd;
- }
- /*
- * check if we can read RTC counter, if not then the RTC is probably
- * not functional. If it isn't probably best to not bind.
- */
- ret = regmap_read(rtc->serial, RTC_COUNTER, &tm);
- if (ret) {
- dev_err(dev, "cannot read RTC counter, RTC not functional\n");
- goto out_disable_vdd;
- }
- meson_rtc_nvmem_config.priv = rtc;
- ret = devm_rtc_nvmem_register(rtc->rtc, &meson_rtc_nvmem_config);
- if (ret)
- goto out_disable_vdd;
- ret = devm_rtc_register_device(rtc->rtc);
- if (ret)
- goto out_disable_vdd;
- return 0;
- out_disable_vdd:
- regulator_disable(rtc->vdd);
- return ret;
- }
- static const __maybe_unused struct of_device_id meson_rtc_dt_match[] = {
- { .compatible = "amlogic,meson6-rtc", },
- { .compatible = "amlogic,meson8-rtc", },
- { .compatible = "amlogic,meson8b-rtc", },
- { .compatible = "amlogic,meson8m2-rtc", },
- { },
- };
- MODULE_DEVICE_TABLE(of, meson_rtc_dt_match);
- static struct platform_driver meson_rtc_driver = {
- .probe = meson_rtc_probe,
- .driver = {
- .name = "meson-rtc",
- .of_match_table = of_match_ptr(meson_rtc_dt_match),
- },
- };
- module_platform_driver(meson_rtc_driver);
- MODULE_DESCRIPTION("Amlogic Meson RTC Driver");
- MODULE_AUTHOR("Ben Dooks <[email protected]>");
- MODULE_AUTHOR("Martin Blumenstingl <[email protected]>");
- MODULE_LICENSE("GPL v2");
- MODULE_ALIAS("platform:meson-rtc");
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