* [rtc-linux] [PATCH v4 1/2] rtc: support for amlogic meson rtc
2016-07-12 17:16 [rtc-linux] [PATCH v4 0/2] AMLogic Meson SoC RTC driver Ben Dooks
@ 2016-07-12 17:16 ` Ben Dooks
2016-07-12 17:16 ` [rtc-linux] [PATCH v4 2/2] meson-rtc: add device-tree binding Ben Dooks
2016-07-12 17:23 ` [rtc-linux] Re: [PATCH v4 0/2] AMLogic Meson SoC RTC driver Alexandre Belloni
2 siblings, 0 replies; 4+ messages in thread
From: Ben Dooks @ 2016-07-12 17:16 UTC (permalink / raw)
To: linux-kernel, linux-amlogic, rtc-linux
Cc: a.zummo, alexandre.belloni, devicetree, narmstrong, khilman,
Ben Dooks
Add support for the AMLogic meson8b/meson6 RTC block.
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Tested-by: Kevin Hilman <khilman@baylibre.com>
---
V4:
- Added Kevin Hilman's tested-by
V3..V1:
- Fixed alpha-ordering in Kconfig
- Fixed checkpatch errors
- Added basic driver information
- Re-organised static-register access functions above rtc driver layer
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
---
drivers/rtc/Kconfig | 9 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-meson.c | 349 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 359 insertions(+)
create mode 100644 drivers/rtc/rtc-meson.c
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 18639e0..6f4097e 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1181,6 +1181,15 @@ config RTC_DRV_ASM9260
This driver can also be built as a module. If so, the module
will be called rtc-asm9260.
+config RTC_DRV_MESON
+ tristate "AMLogic Meson Real Time Clock"
+ depends on ARCH_MESON || COMPILE_TEST
+ help
+ Support for AMLogic Meson RTC block.
+
+ This driver can also be built as a module, if so, the module
+ will be called "rtc-meson".
+
config RTC_DRV_DAVINCI
tristate "TI DaVinci RTC"
depends on ARCH_DAVINCI_DM365 || COMPILE_TEST
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index ea28337..0b4f106 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_RTC_DRV_MAX8997) += rtc-max8997.o
obj-$(CONFIG_RTC_DRV_MAX8998) += rtc-max8998.o
obj-$(CONFIG_RTC_DRV_MC13XXX) += rtc-mc13xxx.o
obj-$(CONFIG_RTC_DRV_MCP795) += rtc-mcp795.o
+obj-$(CONFIG_RTC_DRV_MESON) += rtc-meson.o
obj-$(CONFIG_RTC_DRV_MOXART) += rtc-moxart.o
obj-$(CONFIG_RTC_DRV_MPC5121) += rtc-mpc5121.o
obj-$(CONFIG_RTC_DRV_VRTC) += rtc-mrst.o
diff --git a/drivers/rtc/rtc-meson.c b/drivers/rtc/rtc-meson.c
new file mode 100644
index 0000000..b40b0c9
--- /dev/null
+++ b/drivers/rtc/rtc-meson.c
@@ -0,0 +1,349 @@
+/* drivers/rtc/rtc-meson.c
+ *
+ * RTC driver for the interal RTC block in the AMlogic 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) 2015 Codethink Ltd
+ * Ben Dooks <ben.dooks@codethink.co.uk>
+ * Based on origin by Carlo Caione <carlo@endlessm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/reset.h>
+#include <linux/rtc.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+/* registers accessed from cpu bus */
+#define RTC_REG(x) ((x) * 4) /* rtc registers 0-4 */
+
+#define LINE_SDI (1 << 2)
+#define LINE_SEN (1 << 1)
+#define LINE_SCLK (1 << 0)
+
+#define RTCREG0_START_SER BIT(17)
+#define RTCREG0_WAIT_SER BIT(22)
+#define RTC_REG0_DATA(__data) ((__data) << 24)
+
+#define RTCREG1_READY BIT(1)
+
+/* rtc registers accessed via rtc-serial interface */
+#define RTC_COUNTER (0)
+#define RTC_SEC_ADJ (2)
+
+#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 mutex lock; /* rtc lock */
+ void __iomem *regs; /* rtc register access */
+};
+
+/* RTC front-end serialiser controls */
+
+static void meson_rtc_setline(struct meson_rtc *rtc,
+ unsigned int bit, unsigned int to)
+{
+ u32 reg0;
+
+ reg0 = readl(rtc->regs + RTC_REG(0));
+ if (to)
+ reg0 |= bit;
+ else
+ reg0 &= ~bit;
+ writel(reg0, rtc->regs + RTC_REG(0));
+}
+
+static void meson_rtc_sclk_pulse(struct meson_rtc *rtc)
+{
+ udelay(5);
+ meson_rtc_setline(rtc, LINE_SCLK, 0);
+ udelay(5);
+ meson_rtc_setline(rtc, LINE_SCLK, 1);
+}
+
+static void meson_rtc_send_bit(struct meson_rtc *rtc, unsigned int bit)
+{
+ meson_rtc_setline(rtc, LINE_SDI, bit ? 1 : 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)
+{
+ meson_rtc_setline(rtc, LINE_SEN, 0);
+ meson_rtc_setline(rtc, LINE_SDI, 0);
+ meson_rtc_send_bit(rtc, mode);
+ meson_rtc_setline(rtc, LINE_SDI, 0);
+}
+
+static u32 meson_rtc_read_sdo(struct meson_rtc *rtc)
+{
+ return readl(rtc->regs + RTC_REG(1)) & BIT(0);
+}
+
+static u32 meson_rtc_get_data(struct meson_rtc *rtc)
+{
+ u32 val = 0;
+ int bit;
+
+ for (bit = 0; bit < RTC_DATA_BITS; bit++) {
+ meson_rtc_sclk_pulse(rtc);
+ val <<= 1;
+ val |= meson_rtc_read_sdo(rtc);
+ }
+
+ return val;
+}
+
+static int meson_rtc_wait_bus(struct meson_rtc *rtc, unsigned int timeout_ms)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);
+ u32 val;
+
+ while (time_before(jiffies, timeout)) {
+ val = readl(rtc->regs + RTC_REG(1));
+ if (val & RTCREG1_READY)
+ return 1;
+
+ dev_dbg(rtc->dev, "%s: reg0=%08x reg1=%08x\n",
+ __func__, readl(rtc->regs + RTC_REG(0)), val);
+ msleep(10);
+ }
+
+ return 0;
+}
+
+static int meson_rtc_get_bus(struct meson_rtc *rtc)
+{
+ int ret, retries = 3;
+ u32 val;
+
+ /* prepare bus for transfers, set all lines low */
+ val = readl(rtc->regs + RTC_REG(0));
+ val &= ~(LINE_SDI | LINE_SEN | LINE_SCLK);
+ writel(val, rtc->regs + RTC_REG(0));
+
+ while (retries) {
+ if (meson_rtc_wait_bus(rtc, 300))
+ return 0;
+
+ dev_warn(rtc->dev, "failed to get bus, re-setting\n");
+
+ retries--;
+ ret = reset_control_reset(rtc->reset);
+ if (ret)
+ return ret;
+ }
+
+ dev_err(rtc->dev, "%s: bus is not ready\n", __func__);
+ return -ETIMEDOUT;
+}
+
+static int meson_rtc_read(struct meson_rtc *rtc, unsigned int reg, u32 *data)
+{
+ int ret;
+
+ ret = meson_rtc_get_bus(rtc);
+ if (ret)
+ return ret;
+
+ meson_rtc_setline(rtc, LINE_SEN, 1);
+ 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_write(struct meson_rtc *rtc, unsigned int reg, u32 data)
+{
+ int ret;
+
+ dev_dbg(rtc->dev, "%s: reg %d val %08x)\n", __func__, reg, data);
+
+ ret = meson_rtc_get_bus(rtc);
+ if (ret)
+ return ret;
+
+ meson_rtc_setline(rtc, LINE_SEN, 1);
+ 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 int meson_rtc_wait_serialiser(struct meson_rtc *rtc)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(100);
+
+ while (time_before(jiffies, timeout)) {
+ if (!(readl(rtc->regs + RTC_REG(0)) & RTCREG0_WAIT_SER))
+ return 0;
+ msleep(10);
+ }
+
+ return -ETIMEDOUT;
+}
+
+static int meson_rtc_write_static(struct meson_rtc *rtc, u32 data)
+{
+ u32 tmp;
+ int ret = 0;
+
+ mutex_lock(&rtc->lock);
+
+ writel(data >> 8, rtc->regs + RTC_REG(4));
+
+ tmp = readl(rtc->regs + RTC_REG(0));
+ tmp &= ~RTC_REG0_DATA(0xff);
+ tmp |= RTC_REG0_DATA(data);
+ tmp |= RTCREG0_START_SER;
+ writel(tmp, rtc->regs + RTC_REG(0));
+
+ if (meson_rtc_wait_serialiser(rtc))
+ ret = -ETIMEDOUT;
+
+ dev_dbg(rtc->dev, "%s: ret=%d, rtc_reg0 = %08x\n",
+ __func__, ret, readl(rtc->regs + RTC_REG(0)));
+ mutex_unlock(&rtc->lock);
+
+ return ret;
+}
+
+/* RTC interface layer functions */
+
+static int meson_rtc_gettime(struct device *dev, struct rtc_time *tm)
+{
+ struct meson_rtc *rtc = dev_get_drvdata(dev);
+ int ret;
+ u32 time;
+
+ mutex_lock(&rtc->lock);
+
+ ret = meson_rtc_read(rtc, RTC_COUNTER, &time);
+ if (!ret) {
+ rtc_time_to_tm(time, tm);
+ dev_dbg(dev, "read time %lu\n", (unsigned long)time);
+ }
+
+ mutex_unlock(&rtc->lock);
+ return ret;
+}
+
+static int meson_rtc_settime(struct device *dev, struct rtc_time *tm)
+{
+ struct meson_rtc *rtc = dev_get_drvdata(dev);
+ unsigned long time;
+ int ret;
+
+ mutex_lock(&rtc->lock);
+
+ rtc_tm_to_time(tm, &time);
+ ret = meson_rtc_write(rtc, RTC_COUNTER, time);
+
+ mutex_unlock(&rtc->lock);
+ return ret;
+}
+
+static const struct rtc_class_ops meson_rtc_ops = {
+ .read_time = meson_rtc_gettime,
+ .set_time = meson_rtc_settime,
+};
+
+static int meson_rtc_probe(struct platform_device *pdev)
+{
+ struct meson_rtc *rtc;
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ u32 tm;
+ int ret;
+
+ rtc = devm_kzalloc(dev, sizeof(struct meson_rtc), GFP_KERNEL);
+ if (!rtc)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ rtc->regs = devm_ioremap_resource(dev, res);
+ rtc->dev = dev;
+
+ if (IS_ERR(rtc->regs))
+ return PTR_ERR(rtc->regs);
+
+ mutex_init(&rtc->lock);
+ platform_set_drvdata(pdev, rtc);
+
+ ret = meson_rtc_write_static(rtc, MESON_STATIC_DEFAULT);
+ if (ret) {
+ dev_err(dev, "failed to set static values\n");
+ return ret;
+ }
+
+ rtc->reset = devm_reset_control_get(dev, NULL);
+ if (IS_ERR(rtc->reset))
+ dev_warn(dev, "no reset available, rtc may not work\n");
+
+ /* 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 = meson_rtc_read(rtc, RTC_COUNTER, &tm);
+ if (ret) {
+ dev_err(dev, "cannot read RTC counter, RTC not functional\n");
+ return ret;
+ }
+
+ rtc->rtc = devm_rtc_device_register(dev, "meson",
+ &meson_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc->rtc))
+ return PTR_ERR(rtc->rtc);
+
+ return 0;
+}
+
+static const struct of_device_id meson_rtc_dt_match[] = {
+ { .compatible = "amlogic,meson6-rtc", },
+ { .compatible = "amlogic,meson8-rtc", },
+ { .compatible = "amlogic,meson8b-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 <ben.doosk@codethink.co.uk>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:meson-rtc");
--
2.8.1
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