Re: [rtc-linux] Re: [RFC v1 PATCH 6/6] drivers: rtc: Add supportfor Qualcomm PMIC8058 RTC

From: Anirudh Ghayal
Date: Fri Nov 12 2010 - 10:18:08 EST

Hi Peter,

Trilok Soni wrote:
From: Anirudh Ghayal<aghayal@xxxxxxxxxxxxxx>

PMIC8058 is Qualcomm's power management IC. A
32-bit RTC is housed inside this PMIC. The RTC driver
uses SSBI to communicate with the RTC module.

Cc: Alessandro Zummo<a.zummo@xxxxxxxxxxxx>
Signed-off-by: Anirudh Ghayal<aghayal@xxxxxxxxxxxxxx>
---
drivers/rtc/Kconfig | 9 +
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-pm8058.c | 487 ++++++++++++++++++++++++++++++++++++++++
include/linux/rtc/rtc-pm8058.h | 29 +++
4 files changed, 526 insertions(+), 0 deletions(-)
create mode 100644 drivers/rtc/rtc-pm8058.c
create mode 100644 include/linux/rtc/rtc-pm8058.h

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 2883428..9f4ea00 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -665,6 +665,15 @@ config RTC_DRV_NUC900
If you say yes here you get support for the RTC subsystem of the
NUC910/NUC920 used in embedded systems.

+config RTC_DRV_PM8058
+ tristate "Qualcomm PMIC8058 RTC"
+ depends on PMIC8058
+ help
+ Say Y here if you want to support the Qualcomm PMIC8058 RTC.
+
+ To compile this driver as a module, choose M here: the
+ module will be called pmic8058-rtc.
+
comment "on-CPU RTC drivers"

config RTC_DRV_DAVINCI
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 4c2832d..d7a4f7d 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -73,6 +73,7 @@ obj-$(CONFIG_RTC_DRV_PCF8563) += rtc-pcf8563.o
obj-$(CONFIG_RTC_DRV_PCF8583) += rtc-pcf8583.o
obj-$(CONFIG_RTC_DRV_PCF2123) += rtc-pcf2123.o
obj-$(CONFIG_RTC_DRV_PCF50633) += rtc-pcf50633.o
+obj-$(CONFIG_RTC_DRV_PM8058) += rtc-pm8058.o
obj-$(CONFIG_RTC_DRV_PL030) += rtc-pl030.o
obj-$(CONFIG_RTC_DRV_PL031) += rtc-pl031.o
obj-$(CONFIG_RTC_DRV_PS3) += rtc-ps3.o
diff --git a/drivers/rtc/rtc-pm8058.c b/drivers/rtc/rtc-pm8058.c
new file mode 100644
index 0000000..9fef82d
--- /dev/null
+++ b/drivers/rtc/rtc-pm8058.c
@@ -0,0 +1,487 @@
+/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include<linux/module.h>
+#include<linux/init.h>
+#include<linux/rtc.h>
+#include<linux/mfd/pmic8058.h>
+#include<linux/pm.h>
+#include<linux/slab.h>
+#include<linux/rtc/rtc-pm8058.h>
+
+/* RTC control registers */
+#define PM8058_RTC_CTRL 0x1E8
+#define PM8058_RTC_ALARM_CTRL 0x1E9
+#define PM8058_RTC_TEST 0x1F6
+
+/* RTC register bases */
+#define PM8058_RTC_READ_BASE 0x1EE
+#define PM8058_RTC_WRITE_BASE 0x1EA
+#define PM8058_RTC_ALARM_BASE 0x1F2
+
+/* RTC_CTRL register bit fields */
+#define PM8058_RTC_ENABLE BIT(7)
+#define PM8058_RTC_ALARM_ENABLE BIT(1)

Are there other bits in the ctrl register which are not touch by this driver?
If not you could turn the read-modify-write operations changing the ctrl register
into simple writes.


I will check this. I think this should be possible.

+
+#define NUM_8_BIT_RTC_REGS 0x4
+
+/**
+ * struct pm8058_rtc - rtc driver internal structure
+ * @rtc0 - rtc device for this driver
+ * @rtc_irq - rtc irq number
+ * @rtc_alarm_irq - rtc alarm irq number
+ * @pm_chip - pointer to pm8058 parent structure
+ */
+struct pm8058_rtc {
+ struct rtc_device *rtc0;
Is there a reason for the '0'?

No specific reason for this. I will remove the '0'.

+ int rtc_irq;
+ int rtc_alarm_irq;
+ struct pm8058_chip *pm_chip;
+};
+
+static int
+pm8058_rtc_read_bytes(struct pm8058_rtc *rtc_dd, u8 *rtc_val, int base)
+{
+ int i, rc;
+
+ /* Read the 32-bit register value, 8 bits at a time. */
+ for (i = 0; i< NUM_8_BIT_RTC_REGS; i++) {
+ rc = pm8058_read(rtc_dd->pm_chip, base + i,&rtc_val[i], 1);
+ if (rc< 0) {
+ pr_err("PM8058 read failed\n");
+ return rc;
+ }
+ }
Hm, I don't know the hardware, but I would assume that
pm8058_read(rtc_dd->pm_chip, base, rtc_val, NUM_8_BIT_RTC_REGS) should work as well.

I did try this earlier but the RTC register does not get updated/return a correct 32-bit value. It needs indivisual 8-bit SBI operations.

+
+ return 0;
+}
+
+static int
+pm8058_rtc_write_bytes(struct pm8058_rtc *rtc_dd, u8 *rtc_val, int base)
+{
+ int i, rc;
+
+ /* Write the 32-bit register value, 8 bits at a time. */
+ for (i = 0; i< NUM_8_BIT_RTC_REGS; i++) {
+ rc = pm8058_write(rtc_dd->pm_chip, base + i,&rtc_val[i], 1);
+ if (rc< 0) {
+ pr_err("PM8058 read failed\n");
+ return rc;
+ }
+ }
+
Same here
+ return 0;
+}
+
+/*
+ * Steps to write the RTC registers.
+ * 1. Disable alarm if enabled.
+ * 2. Write 0x00 to LSB.
+ * 3. Write Byte[1], Byte[2], Byte[3] then Byte[0].
+ * 4. Enable alarm if disabled in step 1.
+ */
+static int
+pm8058_rtc0_set_time(struct device *dev, struct rtc_time *tm)
+{
+ int rc;
+ unsigned long secs = 0;
+ u8 value[4], reg = 0, alarm_enabled = 0, ctrl_reg = 0, i;
+ struct pm8058_rtc *rtc_dd = dev_get_drvdata(dev);
+
+ rtc_tm_to_time(tm,&secs);
+
+ value[0] = secs& 0xFF;
+ value[1] = (secs>> 8)& 0xFF;
+ value[2] = (secs>> 16)& 0xFF;
+ value[3] = (secs>> 24)& 0xFF;
+
+ pr_debug("Seconds value to be written to RTC = %lu\n", secs);
+
+ /* Disable alarm before updating RTC */
+ rc = pm8058_read(rtc_dd->pm_chip, PM8058_RTC_CTRL,&ctrl_reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 read failed\n");
dev_err instead of pr_err. The other pr_err should also be replaced.

Ok

+ return rc;
+ }
+
+ if (ctrl_reg& PM8058_RTC_ALARM_ENABLE) {
+ alarm_enabled = 1;
+ ctrl_reg&= ~PM8058_RTC_ALARM_ENABLE;
+ rc = pm8058_write(rtc_dd->pm_chip, PM8058_RTC_CTRL,
+ &ctrl_reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 write failed\n");
+ return rc;
+ }
+ }
+
+ /* Write Byte[1], Byte[2], Byte[3], Byte[0] */
+ reg = 0;
+ rc = pm8058_write(rtc_dd->pm_chip, PM8058_RTC_WRITE_BASE,&reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 write failed\n");
+ return rc;
+ }
+
+ for (i = 1; i< NUM_8_BIT_RTC_REGS; i++) {
+ rc = pm8058_write(rtc_dd->pm_chip, PM8058_RTC_WRITE_BASE + i,
+ &value[i], 1);
+ if (rc< 0) {
+ pr_err("Write to RTC registers failed\n");
+ return rc;
+ }
+ }
+
+ rc = pm8058_write(rtc_dd->pm_chip, PM8058_RTC_WRITE_BASE,
+ &value[0], 1);
+ if (rc< 0) {
+ pr_err("PM8058 write failed\n");
+ return rc;
+ }
+
+ if (alarm_enabled) {
+ ctrl_reg |= PM8058_RTC_ALARM_ENABLE;
+ rc = pm8058_write(rtc_dd->pm_chip, PM8058_RTC_CTRL,
+ &ctrl_reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 write failed\n");
+ return rc;
+ }
+ }
+
+ return 0;
+}
+
+static int
+pm8058_rtc0_read_time(struct device *dev, struct rtc_time *tm)
+{
+ int rc;
+ u8 value[4], reg;
+ unsigned long secs = 0;
+ struct pm8058_rtc *rtc_dd = dev_get_drvdata(dev);
+
+ rc = pm8058_rtc_read_bytes(rtc_dd, value, PM8058_RTC_READ_BASE);
+ if (rc< 0) {
+ pr_err("RTC time read failed\n");
+ return rc;
+ }
+
+ /*
+ * Read the LSB again and check if there has been a carry over.
+ * If there is, redo the read operation.
+ */
+ rc = pm8058_read(rtc_dd->pm_chip, PM8058_RTC_READ_BASE,&reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 read failed\n");
+ return rc;
+ }
+
+ if (unlikely(reg< value[0])) {
+ rc = pm8058_rtc_read_bytes(rtc_dd, value,
+ PM8058_RTC_READ_BASE);
+ if (rc< 0) {
+ pr_err("RTC time read failed\n");
+ return rc;
+ }
+ }
+
+ secs = value[0] | (value[1]<< 8) | (value[2]<< 16) | (value[3]<< 24);
+
+ rtc_time_to_tm(secs, tm);
+
+ rc = rtc_valid_tm(tm);
+ if (rc< 0) {
+ pr_err("Invalid time read from PMIC8058\n");
+ return rc;
+ }
+
+ pr_debug("secs = %lu, h::m:s == %d::%d::%d, d/m/y = %d/%d/%d\n",
+ secs, tm->tm_hour, tm->tm_min, tm->tm_sec,
+ tm->tm_mday, tm->tm_mon, tm->tm_year);
+
+ return 0;
+}
+
+static int
+pm8058_rtc0_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ int rc;
+ u8 value[4], reg;
+ unsigned long secs = 0;
No need to initialize secs here.

Ok

+ struct pm8058_rtc *rtc_dd = dev_get_drvdata(dev);
+
+ /* Check if a alarm is valid */
+ rc = rtc_valid_tm(&alarm->time);
+ if (rc< 0) {
+ pr_err("Alarm time invalid\n");
+ return -EINVAL;
+ }
The upper layer will already check if alarm->time is valid, so there is no need to
check it here again.

I see. I will remove this.

+
+ rtc_tm_to_time(&alarm->time,&secs);
+
+ value[0] = secs& 0xFF;
+ value[1] = (secs>> 8)& 0xFF;
+ value[2] = (secs>> 16)& 0xFF;
+ value[3] = (secs>> 24)& 0xFF;
+
+ rc = pm8058_rtc_write_bytes(rtc_dd, value, PM8058_RTC_ALARM_BASE);
+ if (rc< 0) {
+ pr_err("Alarm could not be set\n");
+ return rc;
+ }
+
+ rc = pm8058_read(rtc_dd->pm_chip, PM8058_RTC_CTRL,&reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 read failed\n");
+ return rc;
+ }
+
+ reg = (alarm->enabled) ? (reg | PM8058_RTC_ALARM_ENABLE) :
+ (reg& ~PM8058_RTC_ALARM_ENABLE);
+
+ rc = pm8058_write(rtc_dd->pm_chip, PM8058_RTC_CTRL,&reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 write failed\n");
+ return rc;
+ }
+
+ pr_debug("Alarm Set for h:r:s=%d:%d:%d, d/m/y=%d/%d/%d\n",
+ alarm->time.tm_hour, alarm->time.tm_min,
+ alarm->time.tm_sec, alarm->time.tm_mday,
+ alarm->time.tm_mon, alarm->time.tm_year);
+
+ return 0;
+}
+
+static int
+pm8058_rtc0_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ int rc;
+ u8 value[4], reg;
+ unsigned long secs = 0;
No need to initialize secs here.

Ok

+ struct pm8058_rtc *rtc_dd = dev_get_drvdata(dev);
+
+ /* Check if the alarm is enabled */
+ rc = pm8058_read(rtc_dd->pm_chip, PM8058_RTC_CTRL,&reg, 1);
+ if (rc< 0) {
+ pr_err("PM8058 read failed\n");
+ return rc;
+ }
+ alarm->enabled = !!(reg& PM8058_RTC_ALARM_ENABLE);
+
+ rc = pm8058_rtc_read_bytes(rtc_dd, value,
+ PM8058_RTC_ALARM_BASE);
+ if (rc< 0) {
+ pr_err("RTC alarm time read failed\n");
+ return rc;
+ }
+
+ secs = value[0] | (value[1]<< 8) | (value[2]<< 16) | (value[3]<< 24);
+
+ rtc_time_to_tm(secs,&alarm->time);
+
+ rc = rtc_valid_tm(&alarm->time);
+ if (rc< 0) {
+ pr_err("Invalid time read from PMIC8058\n");
+ return rc;
+ }
+
+ pr_debug("Alarm set for - h:r:s=%d:%d:%d, d/m/y=%d/%d/%d\n",
+ alarm->time.tm_hour, alarm->time.tm_min,
+ alarm->time.tm_sec, alarm->time.tm_mday,
+ alarm->time.tm_mon, alarm->time.tm_year);
+
+ return 0;
+}
+
+static struct rtc_class_ops pm8058_rtc0_ops = {
+ .read_time = pm8058_rtc0_read_time,
+ .set_alarm = pm8058_rtc0_set_alarm,
+ .read_alarm = pm8058_rtc0_read_alarm,

Implementig alarm_irq_enable might be a good idea

Ok, I'll try to add the other supported ops as well.


+};
+
+static irqreturn_t pm8058_alarm_trigger(int irq, void *dev_id)
+{
+ unsigned long events = 0;
+ struct pm8058_rtc *rtc_dd = dev_id;
+
+ events = RTC_IRQF | RTC_AF;
+ rtc_update_irq(rtc_dd->rtc0, 1, events);

just rtc_update_irq(rtc_dd->rtc0, 1, RTC_IRQF | RTC_AF); should be fine

Ok


+
+ pr_debug("Alarm Triggered !!\n");
+
+ return IRQ_HANDLED;
+}
+
+static int __devinit pm8058_rtc_probe(struct platform_device *pdev)
+{
+ int rc;
+ u8 reg;
+ struct pm8058_rtc *rtc_dd;
+ struct pm8058_chip *pm_chip;
+ struct pm8058_rtc_pdata *pdata = pdev->dev.platform_data;
+
+ if (pdata == NULL) {
+ dev_err(&pdev->dev, "Platform data absent!\n");
+ return -ENXIO;
+ }
It might be a good idea to assume a default for rtc_write_enable if pdata is not set.

Yes, makes sense.

+
+ pm_chip = platform_get_drvdata(pdev);
+ if (pm_chip == NULL) {
+ dev_err(&pdev->dev, "Invalid driver information!\n");
+ return -ENXIO;
+ }
+
+ rtc_dd = kzalloc(sizeof(*rtc_dd), GFP_KERNEL);
+ if (rtc_dd == NULL) {
+ dev_err(&pdev->dev, "Unable to allocate memory!\n");
+ return -ENOMEM;
+ }
+
+ rtc_dd->rtc_irq = platform_get_irq(pdev, 0);
You don't seem to use this irq.

This was for the RTC tick interrupt. I will remove this code.


+ rtc_dd->rtc_alarm_irq = platform_get_irq(pdev, 1);
+ if (!rtc_dd->rtc_alarm_irq || !rtc_dd->rtc_irq) {
+ dev_err(&pdev->dev, "RTC / Alarm IRQ resource absent!\n");
+ rc = -ENXIO;
+ goto fail_rtc_enable;
+ }
+
+ rtc_dd->pm_chip = pm_chip;
+
+ /* Check if the RTC is on, else turn it on */
+ rc = pm8058_read(pm_chip, PM8058_RTC_CTRL,&reg, 1);
+ if (rc< 0) {
+ dev_err(&pdev->dev, "PM8058 read failed!\n");
+ goto fail_rtc_enable;
+ }
+
+ if (!(reg& PM8058_RTC_ENABLE)) {
+ reg |= PM8058_RTC_ENABLE;
+ rc = pm8058_write(pm_chip, PM8058_RTC_CTRL,&reg, 1);
+ if (rc< 0) {
+ dev_err(&pdev->dev, "PM8058 write failed!\n");
+ goto fail_rtc_enable;
+ }
+ }
+
+ if (pdata->rtc_write_enable == true)
+ pm8058_rtc0_ops.set_time = pm8058_rtc0_set_time,
+
+ /* Register the RTC device */
+ rtc_dd->rtc0 = rtc_device_register("pm8058_rtc0",&pdev->dev,
+ &pm8058_rtc0_ops, THIS_MODULE);
+ if (IS_ERR(rtc_dd->rtc0)) {
+ dev_err(&pdev->dev, "%s: RTC registration failed (%ld)\n",
+ __func__, PTR_ERR(rtc_dd->rtc0));
+ rc = PTR_ERR(rtc_dd->rtc0);
+ goto fail_rtc_enable;
+ }
+
+ platform_set_drvdata(pdev, rtc_dd);
+
+ /* Request the alarm IRQ */
+ rc = request_any_context_irq(rtc_dd->rtc_alarm_irq,
+ pm8058_alarm_trigger, IRQF_TRIGGER_RISING,
+ "pm8058_rtc_alarm", rtc_dd);
+ if (rc< 0) {
+ dev_err(&pdev->dev, "Request IRQ failed (%d)\n", rc);
+ goto fail_req_irq;
+ }
+
+ device_init_wakeup(&pdev->dev, 1);
+
+ dev_dbg(&pdev->dev, "Probe success !!\n");
+
+ return 0;
+
+fail_req_irq:
+ rtc_device_unregister(rtc_dd->rtc0);
+fail_rtc_enable:
+ kfree(rtc_dd);
+ return rc;
+}
+
+#ifdef CONFIG_PM
+static int pm8058_rtc_resume(struct device *dev)
+{
+ struct pm8058_rtc *rtc_dd = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ disable_irq_wake(rtc_dd->rtc_alarm_irq);
+
+ return 0;
+}
+
+static int pm8058_rtc_suspend(struct device *dev)
+{
+ struct pm8058_rtc *rtc_dd = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ enable_irq_wake(rtc_dd->rtc_alarm_irq);
+
+ return 0;
+}
+
+static const struct dev_pm_ops pm8058_rtc_pm_ops = {
+ .suspend = pm8058_rtc_suspend,
+ .resume = pm8058_rtc_resume,
+};
+#endif
+
+static int __devexit pm8058_rtc_remove(struct platform_device *pdev)
+{
+ struct pm8058_rtc *rtc_dd = platform_get_drvdata(pdev);
+
+ device_init_wakeup(&pdev->dev, 0);
+ free_irq(rtc_dd->rtc_alarm_irq, rtc_dd);
+ rtc_device_unregister(rtc_dd->rtc0);
+ kfree(rtc_dd);
+
+ return 0;
+}
+
+static struct platform_driver pm8058_rtc_driver = {
+ .probe = pm8058_rtc_probe,
+ .remove = __devexit_p(pm8058_rtc_remove),
+ .driver = {
+ .name = "pm8058-rtc",
+ .owner = THIS_MODULE,
+#ifdef CONFIG_PM
+ .pm =&pm8058_rtc_pm_ops,
+#endif
+ },
+};
+
+static int __init pm8058_rtc_init(void)
+{
+ return platform_driver_register(&pm8058_rtc_driver);
+}
+
+static void __exit pm8058_rtc_exit(void)
+{
+ platform_driver_unregister(&pm8058_rtc_driver);
+}
+
+module_init(pm8058_rtc_init);
+module_exit(pm8058_rtc_exit);
module_{init,exit} should go right beneath the function they are referring to

Ok.


+
+MODULE_ALIAS("platform:pm8058-rtc");
+MODULE_DESCRIPTION("PMIC8058 RTC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(Anirudh Ghayal "<aghayal@xxxxxxxxxxxxxx>");
diff --git a/include/linux/rtc/rtc-pm8058.h b/include/linux/rtc/rtc-pm8058.h
new file mode 100644
index 0000000..51f7c0b
--- /dev/null
+++ b/include/linux/rtc/rtc-pm8058.h
@@ -0,0 +1,29 @@
+/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef __RTC_PM8058_H__
+#define __RTC_PM8058_H__
+
+/**
+ * struct pm8058_rtc_pdata - RTC driver platform data
+ * @rtc_write_enable - variable stating RTC write capability
+ */
+struct pm8058_rtc_pdata {
+ bool rtc_write_enable;
+};
Is there a technical reason why changing the rtc clocks time should be disabled or is
this a policy based decision?

In some of our MSM/QSD designs, we have a single RTC shared by multiple processors (other than the ones running Linux). Thus, the need to have a non-writable RTC using this pdata.

+
+#endif /* __RTC_PM8058_H__ */


Thank you for the detailed review. I will make these changes in my next patch.

--Anirudh

--
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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