[PATCH u-boot-marvell v2 1/4] rtc: add armada38x driver
Pali Rohár
pali at kernel.org
Sun Mar 28 21:24:16 CEST 2021
On Friday 26 February 2021 10:30:19 Marek Behún wrote:
> Add RTC driver for Armada 38x, based on Linux' driver.
> For now implement only `marvell,armada-380-rtc` compatible.
>
> Signed-off-by: Marek Behún <marek.behun at nic.cz>
> Reviewed-by: Stefan Roese <sr at denx.de>
> Cc: Pali Rohár <pali at kernel.org>
Acked-by: Pali Rohár <pali at kernel.org>
> Cc: Baruch Siach <baruch at tkos.co.il>
> Cc: Chris Packham <judge.packham at gmail.com>
> Cc: Simon Glass <sjg at chromium.org>
> ---
> drivers/rtc/Kconfig | 7 ++
> drivers/rtc/Makefile | 1 +
> drivers/rtc/armada38x.c | 184 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 192 insertions(+)
> create mode 100644 drivers/rtc/armada38x.c
>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index aa6d90158c..dafba35279 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -38,6 +38,13 @@ config RTC_ENABLE_32KHZ_OUTPUT
> Some real-time clocks support the output of 32kHz square waves (such as ds3231),
> the config symbol choose Real Time Clock device 32Khz output feature.
>
> +config RTC_ARMADA38X
> + bool "Enable Armada 38x Marvell SoC RTC"
> + depends on DM_RTC && ARCH_MVEBU
> + help
> + This adds support for the in-chip RTC that can be found in the
> + Armada 38x Marvell's SoC devices.
> +
> config RTC_PCF2127
> bool "Enable PCF2127 driver"
> depends on DM_RTC
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 6a45a9c874..15609e7b18 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_$(SPL_TPL_)DM_RTC) += rtc-uclass.o
>
> obj-$(CONFIG_RTC_AT91SAM9_RTT) += at91sam9_rtt.o
> obj-y += rtc-lib.o
> +obj-$(CONFIG_RTC_ARMADA38X) += armada38x.o
> obj-$(CONFIG_RTC_DAVINCI) += davinci.o
> obj-$(CONFIG_RTC_DS1302) += ds1302.o
> obj-$(CONFIG_RTC_DS1306) += ds1306.o
> diff --git a/drivers/rtc/armada38x.c b/drivers/rtc/armada38x.c
> new file mode 100644
> index 0000000000..2d264acf77
> --- /dev/null
> +++ b/drivers/rtc/armada38x.c
> @@ -0,0 +1,184 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * RTC driver for the Armada 38x Marvell SoCs
> + *
> + * Copyright (C) 2021 Marek Behun <marek.behun at nic.cz>
> + *
> + * Based on Linux' driver by Gregory Clement and Marvell
> + */
> +
> +#include <asm/io.h>
> +#include <dm.h>
> +#include <linux/delay.h>
> +#include <rtc.h>
> +
> +#define RTC_STATUS 0x0
> +#define RTC_TIME 0xC
> +#define RTC_CONF_TEST 0x1C
> +
> +/* Armada38x SoC registers */
> +#define RTC_38X_BRIDGE_TIMING_CTL 0x0
> +#define RTC_38X_PERIOD_OFFS 0
> +#define RTC_38X_PERIOD_MASK (0x3FF << RTC_38X_PERIOD_OFFS)
> +#define RTC_38X_READ_DELAY_OFFS 26
> +#define RTC_38X_READ_DELAY_MASK (0x1F << RTC_38X_READ_DELAY_OFFS)
> +
> +#define SAMPLE_NR 100
> +
> +struct armada38x_rtc {
> + void __iomem *regs;
> + void __iomem *regs_soc;
> +};
> +
> +/*
> + * According to Erratum RES-3124064 we have to do some configuration in MBUS.
> + * To read an RTC register we need to read it 100 times and return the most
> + * frequent value.
> + * To write an RTC register we need to write 2x zero into STATUS register,
> + * followed by the proper write. Linux adds an 5 us delay after this, so we do
> + * it here as well.
> + */
> +static void update_38x_mbus_timing_params(struct armada38x_rtc *rtc)
> +{
> + u32 reg;
> +
> + reg = readl(rtc->regs_soc + RTC_38X_BRIDGE_TIMING_CTL);
> + reg &= ~RTC_38X_PERIOD_MASK;
> + reg |= 0x3FF << RTC_38X_PERIOD_OFFS; /* Maximum value */
> + reg &= ~RTC_38X_READ_DELAY_MASK;
> + reg |= 0x1F << RTC_38X_READ_DELAY_OFFS; /* Maximum value */
> + writel(reg, rtc->regs_soc + RTC_38X_BRIDGE_TIMING_CTL);
> +}
> +
> +static void armada38x_rtc_write(u32 val, struct armada38x_rtc *rtc, u8 reg)
> +{
> + writel(0, rtc->regs + RTC_STATUS);
> + writel(0, rtc->regs + RTC_STATUS);
> + writel(val, rtc->regs + reg);
> + udelay(5);
> +}
> +
> +static u32 armada38x_rtc_read(struct armada38x_rtc *rtc, u8 reg)
> +{
> + u8 counts[SAMPLE_NR], max_idx;
> + u32 samples[SAMPLE_NR], max;
> + int i, j, last;
> +
> + for (i = 0, last = 0; i < SAMPLE_NR; ++i) {
> + u32 sample = readl(rtc->regs + reg);
> +
> + /* find if this value was already read */
> + for (j = 0; j < last; ++j) {
> + if (samples[j] == sample)
> + break;
> + }
> +
> + if (j < last) {
> + /* if yes, increment count */
> + ++counts[j];
> + } else {
> + /* if not, add */
> + samples[last] = sample;
> + counts[last] = 1;
> + ++last;
> + }
> + }
> +
> + /* finally find the sample that was read the most */
> + max = 0;
> + max_idx = 0;
> +
> + for (i = 0; i < last; ++i) {
> + if (counts[i] > max) {
> + max = counts[i];
> + max_idx = i;
> + }
> + }
> +
> + return samples[max_idx];
> +}
> +
> +static int armada38x_rtc_get(struct udevice *dev, struct rtc_time *tm)
> +{
> + struct armada38x_rtc *rtc = dev_get_priv(dev);
> + u32 time;
> +
> + time = armada38x_rtc_read(rtc, RTC_TIME);
> +
> + rtc_to_tm(time, tm);
> +
> + return 0;
> +}
> +
> +static int armada38x_rtc_reset(struct udevice *dev)
> +{
> + struct armada38x_rtc *rtc = dev_get_priv(dev);
> + u32 reg;
> +
> + reg = armada38x_rtc_read(rtc, RTC_CONF_TEST);
> +
> + if (reg & 0xff) {
> + armada38x_rtc_write(0, rtc, RTC_CONF_TEST);
> + mdelay(500);
> + armada38x_rtc_write(0, rtc, RTC_TIME);
> + armada38x_rtc_write(BIT(0) | BIT(1), 0, RTC_STATUS);
> + }
> +
> + return 0;
> +}
> +
> +static int armada38x_rtc_set(struct udevice *dev, const struct rtc_time *tm)
> +{
> + struct armada38x_rtc *rtc = dev_get_priv(dev);
> + unsigned long time;
> +
> + time = rtc_mktime(tm);
> +
> + if (time > U32_MAX)
> + printf("%s: requested time to set will overflow\n", dev->name);
> +
> + armada38x_rtc_reset(dev);
> + armada38x_rtc_write(time, rtc, RTC_TIME);
> +
> + return 0;
> +}
> +
> +static int armada38x_probe(struct udevice *dev)
> +{
> + struct armada38x_rtc *rtc = dev_get_priv(dev);
> +
> + rtc->regs = dev_remap_addr_name(dev, "rtc");
> + if (!rtc->regs)
> + goto err;
> +
> + rtc->regs_soc = dev_remap_addr_name(dev, "rtc-soc");
> + if (!rtc->regs_soc)
> + goto err;
> +
> + update_38x_mbus_timing_params(rtc);
> +
> + return 0;
> +err:
> + printf("%s: io address missing\n", dev->name);
> + return -ENODEV;
> +}
> +
> +static const struct rtc_ops armada38x_rtc_ops = {
> + .get = armada38x_rtc_get,
> + .set = armada38x_rtc_set,
> + .reset = armada38x_rtc_reset,
> +};
> +
> +static const struct udevice_id armada38x_rtc_ids[] = {
> + { .compatible = "marvell,armada-380-rtc", .data = 0 },
> + { }
> +};
> +
> +U_BOOT_DRIVER(rtc_armada38x) = {
> + .name = "rtc-armada38x",
> + .id = UCLASS_RTC,
> + .of_match = armada38x_rtc_ids,
> + .probe = armada38x_probe,
> + .priv_auto = sizeof(struct armada38x_rtc),
> + .ops = &armada38x_rtc_ops,
> +};
> --
> 2.26.2
>
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