Patchwork [v3,2/2] Add RTC driver for NXP PCF2127A (I2C)

login
register
mail settings
Submitter Torsten Mehnert
Date June 27, 2011, 3:45 p.m.
Message ID <3F263ABB4EDE344D974E1983B56807734FF5E597@EX-DAG02.eckelmann.group>
Download mbox | patch
Permalink /patch/102210/
State New
Headers show

Comments

Torsten Mehnert - June 27, 2011, 3:45 p.m.
Hi,

thanks again for your review. There is no chip named "rtc2127a",
this time it's clear ;-) And the "checkpatch" script is worth gold.

Changes v3:
        - Signed-off-by added
        - Coding-Style issues removed (like whitespaces)
        - "checkpatch" confirmed
        - Removed compatiblity with"rtc2127a", because no such chip exists
        - Fixed an error in probe that cause an unnecessary/doubled memory allocation
        - Removed global static rtc_device pointer, using i2c_get_clientdata instead
        - Fixed MODULE_AUTHOR macro

Changes v2:
        - Fixed spelling mistakes in Kconfig and header
        - <linux/module.h> included
        - DRV_VERSION / MODULE_VERSION removed
        - struct pcf2127a removed, because it has only one member
        - Some unnecessary debug outputs removed
        - Fixed comments to match kernel style guidelines
        - module_init/_exit makros are now placed under the respective function

Thanks for your patience,
        Torsten

From: T. Mehnert <t.mehnert@eckelmann.de>
Date: Mon, 27 Jun 2011 16:29:08 +0200
Subject: [PATCH] RTC pcf2127a i2c implementation

This patch adds the device driver for the RTC NXP PCF2127A.
It only implement the i2c interface to the RTC.

rtc_class_ops: read_time, set_time

Signed-off-by: Torsten Mehnert <t.mehnert@eckelmann.de>
---
 drivers/rtc/Kconfig        |   11 ++
 drivers/rtc/Makefile       |    1 +
 drivers/rtc/rtc-pcf2127a.c |  307 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 319 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-pcf2127a.c

--
1.7.0.4

ECKELMANN AG
Vorstand: Dr.-Ing. Gerd Eckelmann (Vorsitzender), Dr.-Ing. Peter Cordes, Dr.-Ing. Frank-Thomas Mellert
Vorsitzender des Aufsichtsrats: Hubertus G. Krossa
Sitz der Gesellschaft: Wiesbaden
Amtsgericht Wiesbaden, HRB 12636

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index e187887..42bb6ca 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -264,6 +264,17 @@  config RTC_DRV_PCF8583
          This driver can also be built as a module. If so, the module
          will be called rtc-pcf8583.

+config RTC_DRV_PCF2127A
+       tristate "Philips PCF2127A (only I2C)"
+       help
+         If you say yes here you get support for the Philips PCF2127A
+         RTC. This driver implements only the i2c-interface to the chip.
+         It may work with pcf2127, but is tested only against
+         the pcf2127a.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-pcf2127a.
+
 config RTC_DRV_M41T80
        tristate "ST M41T62/65/M41T80/81/82/83/84/85/87"
        help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index dea00e2..ad2ff9b 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -69,6 +69,7 @@  obj-$(CONFIG_RTC_DRV_NUC900)  += rtc-nuc900.o
 obj-$(CONFIG_RTC_DRV_OMAP)     += rtc-omap.o
 obj-$(CONFIG_RTC_DRV_PCAP)     += rtc-pcap.o
 obj-$(CONFIG_RTC_DRV_PCF2123)  += rtc-pcf2123.o
+obj-$(CONFIG_RTC_DRV_PCF2127A) += rtc-pcf2127a.o
 obj-$(CONFIG_RTC_DRV_PCF8563)  += rtc-pcf8563.o
 obj-$(CONFIG_RTC_DRV_PCF8583)  += rtc-pcf8583.o
 obj-$(CONFIG_RTC_DRV_PCF50633) += rtc-pcf50633.o
diff --git a/drivers/rtc/rtc-pcf2127a.c b/drivers/rtc/rtc-pcf2127a.c
new file mode 100644
index 0000000..ed7495f
--- /dev/null
+++ b/drivers/rtc/rtc-pcf2127a.c
@@ -0,0 +1,307 @@ 
+/*
+ * Driver the the NXP/Philips PCF2127A RTC (only I2C)
+ *
+ * Copyright (c) 2011 ECKELMANN AG.
+ *
+ * Authors:    Matthias Wolf  <m.wolf@eckelmann.de>
+ *             Torsten Mehnert <t.mehnert@eckelmann.de>
+ *
+ * RTC-Datasheet: http://www.nxp.com/documents/data_sheet/PCF2127A.pdf
+ *
+ * NOTE: This driver only implements the i2c-interface to the RTC.
+ * This driver is based on rtc-pcf8363 from Alessandro Zummo.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+/* PCF2127A Registers */
+#define PCF2127A_REG_CTL1              0x00 /* Control 1 */
+#define PCF2127A_REG_CTL2              0x01 /* Control 2 */
+#define PCF2127A_REG_CTL3              0x02 /* Control 3 */
+
+#define PCF2127A_REG_SC                        0x03 /* second value    */
+#define PCF2127A_REG_MN                        0x04 /* minute value    */
+#define PCF2127A_REG_HR                        0x05 /* hour value      */
+#define PCF2127A_REG_DM                        0x06 /* day value       */
+#define PCF2127A_REG_DW                        0x07 /* weekday value   */
+#define PCF2127A_REG_MO                        0x08 /* month value     */
+#define PCF2127A_REG_YR                        0x09 /* year value      */
+
+#define PCF2127A_REG_SC_ALARM          0x0A /* second alarm            */
+#define PCF2127A_REG_MN_ALARM          0x0B /* minute alarm            */
+#define PCF2127A_REG_HR_ALARM          0x0C /* hour alarm              */
+#define PCF2127A_REG_DM_ALARM          0x0D /* day alarm               */
+#define PCF2127A_REG_DW_ALARM          0x0E /* weekday alarm           */
+
+#define PCF2127A_REG_CLKO              0x0F /* clock out       */
+#define PCF2127A_REG_WD_TMRC           0x10 /* watchdog timer control  */
+#define PCF2127A_REG_WD_TMVAL          0x11 /* watchdog timer value    */
+
+#define PCF2127A_REG_TSCTL             0x12 /* timestamp control       */
+#define PCF2127A_REG_SC_TS             0x13 /* second timestamp        */
+#define PCF2127A_REG_MN_TS             0x14 /* minute timestamp        */
+#define PCF2127A_REG_HR_TS             0x15 /* hour timestamp          */
+#define PCF2127A_REG_DM_TS             0x16 /* day timestamp           */
+#define PCF2127A_REG_MO_TS             0x17 /* month timestamp         */
+#define PCF2127A_REG_YR_TS             0x18 /* year timestamp          */
+#define PCF2127A_REG_AGI_OFF           0x19 /* aging offset            */
+#define PCF2127A_REG_RAM_MSB           0x1A /* RAM address MSB         */
+#define PCF2127A_REG_RAM_LSB           0x1B /* RAM address LSB         */
+#define PCF2127A_REG_RAM_WCMD          0x1C /* RAM write command       */
+#define PCF2127A_REG_RAM_RCMD          0x1D /* RAM read command        */
+
+/* Bits in PCF2127A_REG_CTL1 */
+#define PCF2127A_BIT_SI                        0x01 /* second interrupt        */
+#define PCF2127A_BIT_MI                        0x02 /* minute interrupt        */
+#define PCF2127A_BIT_H_24_12           0x04 /* 12/24 hour mode         */
+#define PCF2127A_BIT_POR_OVRD          0x08 /* POR override            */
+#define PCF2127A_BIT_TSF1              0x10 /* timestamp flag 1        */
+#define PCF2127A_BIT_STOP              0x20 /* stop bit                */
+#define PCF2127A_BIT_EXTTEST           0x80 /* external clock test mode*/
+
+/* Bits in PCF2127A_REG_CTL2 */
+#define PCF2127A_BIT_CDTIE             0x01 /* countdown timer flag    */
+#define PCF2127A_BIT_AIE               0x02 /* alarm interrupt enable  */
+#define PCF2127A_BIT_TSIE              0x04 /* timestamp int. enable   */
+#define PCF2127A_BIT_CDTF              0x08 /* countdown timer flag    */
+#define PCF2127A_BIT_AF                        0x10 /* alarm flag              */
+#define PCF2127A_BIT_TSF2              0x20 /* timestamp flag 2        */
+#define PCF2127A_BIT_WDTF              0x40 /* watchdog timer flag     */
+#define PCF2127A_BIT_MSF               0x80 /* minute/second flag      */
+
+/* Bits in PCF2127A_REG_CTL3 */
+#define PCF2127A_BIT_BLIE              0x01 /* battery low Interrupt enable */
+#define PCF2127A_BIT_BIE               0x02 /* battery Switch int. enable */
+#define PCF2127A_BIT_BLF               0x04 /* battery low flag        */
+#define PCF2127A_BIT_BF                        0x08 /* battery switch flag     */
+#define PCF2127A_BIT_BTSE              0x10 /* battery timestamp enable */
+#define PCF2127A_BIT_BLDOFF            0x20 /* battery low detection off */
+#define PCF2127A_BIT_BSM               0x40 /* battery switch mode     */
+#define PCF2127A_BIT_BSOFF             0x80 /* battery switch off      */
+
+static struct i2c_driver pcf2127a_driver;
+
+/*
+ * In the routines that deal directly with the pcf2127a hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
+ */
+static
+int pcf2127a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+       unsigned char buf[10] = { PCF2127A_REG_CTL1 };
+
+       /*
+       * Note: We can't use i2c_transfer to send/recv multiple i2c_msg's
+       * to/from pcf2127a at once. The reason is that the pcf2127a doesn't
+       * handle (repeated START)-Conditions correctly.
+       *
+       * PCF2127A Manual, Section 9.2.2 START and STOP conditions:
+       * "Remark: For the PCF2127A a repeated START is not allowed. Therefore
+       * a STOP has to be released before the next START."
+       */
+
+       /* setup read ptr */
+       if (!i2c_master_send(client, buf, 1)) {
+               dev_err(&client->dev, "%s: write error\n", __func__);
+               return -EIO;
+       }
+
+       /* read status + date */
+       if (!i2c_master_recv(client, buf, 10)) {
+               dev_err(&client->dev, "%s: read error\n", __func__);
+               return -EIO;
+       }
+
+       if (buf[PCF2127A_REG_CTL3] & PCF2127A_BIT_BLF)
+               dev_info(&client->dev,
+                       "low battery detected, date/time is not reliable.\n");
+
+#ifdef DEBUG
+       unsigned char bf_buf[2];
+       if (buf[PCF2127A_REG_CTL3] & PCF2127A_BIT_BF) {
+               dev_info(&client->dev,
+                       "battery switch-over detected - reset BF flag.\n");
+
+               bf_buf[0] = PCF2127A_REG_CTL3;
+               bf_buf[1] = buf[PCF2127A_REG_CTL3] & ~PCF2127A_BIT_BF;
+               if (!i2c_master_send(client, bf_buf, 2)) {
+                               dev_err(&client->dev,
+                                       "%s: write error\n", __func__);
+                               return -EIO;
+                       }
+               }
+#endif
+
+       dev_dbg(&client->dev,
+               "%s: raw data is ctl1=%02x, ctl2=%02x, ctl3=%02x, sec=%02x, "
+               "min=%02x, hour=%02x, day=%02x, wday=%02x, month=%02x, "
+               "year=%02x\n",
+               __func__,
+               buf[0], buf[1], buf[2], buf[3],
+               buf[4], buf[5], buf[6], buf[7],
+               buf[8], buf[9]);
+
+       tm->tm_sec = bcd2bin(buf[PCF2127A_REG_SC] & 0x7F);
+       tm->tm_min = bcd2bin(buf[PCF2127A_REG_MN] & 0x7F);
+       tm->tm_hour = bcd2bin(buf[PCF2127A_REG_HR] & 0x3F); /* rtc hr 0-23 */
+       tm->tm_mday = bcd2bin(buf[PCF2127A_REG_DM] & 0x3F);
+       tm->tm_wday = buf[PCF2127A_REG_DW] & 0x07;
+       tm->tm_mon = bcd2bin(buf[PCF2127A_REG_MO] & 0x1F) - 1; /* rtc m 1-12 */
+       tm->tm_year = bcd2bin(buf[PCF2127A_REG_YR]);
+
+       if (tm->tm_year < 70)
+               tm->tm_year += 100;     /* assume we are in 1970...2069 */
+
+       /*
+        * the clock can give out invalid datetime, but we cannot return
+        * -EINVAL otherwise hwclock will refuse to set the time on bootup.
+        */
+       if (rtc_valid_tm(tm) < 0)
+               dev_err(&client->dev, "retrieved date/time is not valid.\n");
+
+       return 0;
+}
+
+static
+int pcf2127a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+       int i, err;
+       unsigned char msgdata[2];       /* send data*/
+       unsigned char buf[10];          /* Index 0 - 9 */
+
+       /* hours, minutes and seconds */
+       buf[PCF2127A_REG_SC] = bin2bcd(tm->tm_sec);
+       buf[PCF2127A_REG_MN] = bin2bcd(tm->tm_min);
+       buf[PCF2127A_REG_HR] = bin2bcd(tm->tm_hour);
+
+       /* day of month */
+       buf[PCF2127A_REG_DM] = bin2bcd(tm->tm_mday);
+
+       /* weekday */
+       buf[PCF2127A_REG_DW] = tm->tm_wday & 0x07;
+
+       /* month, 1 - 12 */
+       buf[PCF2127A_REG_MO] = bin2bcd(tm->tm_mon + 1);
+
+       /* year */
+       buf[PCF2127A_REG_YR] = bin2bcd(tm->tm_year % 100);
+
+       /* write register's data */
+       for (i = 0; i < 7; i++) {
+               msgdata[0] = PCF2127A_REG_SC + i;
+               msgdata[1] = buf[PCF2127A_REG_SC + i];
+               err = i2c_master_send(client, msgdata, sizeof(msgdata));
+               if (err != sizeof(msgdata)) {
+                       dev_err(&client->dev,
+                               "%s: err=%d addr=%02x, data=%02x\n",
+                               __func__, err, msgdata[0], msgdata[1]);
+                       return -EIO;
+               }
+       }
+       return 0;
+}
+
+/*---------------------------------------------------------------------------*/
+
+static int pcf2127a_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+       return pcf2127a_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int pcf2127a_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+       return pcf2127a_set_datetime(to_i2c_client(dev), tm);
+}
+
+static const struct rtc_class_ops pcf2127a_rtc_ops = {
+       .read_time      = pcf2127a_rtc_read_time,
+       .set_time       = pcf2127a_rtc_set_time,
+};
+
+/*---------------------------------------------------------------------------*/
+
+static int pcf2127a_probe(struct i2c_client *client,
+                               const struct i2c_device_id *id)
+{
+       struct rtc_device *pcf2127a_device;
+
+       if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+               return -ENODEV;
+
+       dev_info(&client->dev, "chip found\n");
+
+       pcf2127a_device = rtc_device_register(pcf2127a_driver.driver.name,
+                               &client->dev, &pcf2127a_rtc_ops, THIS_MODULE);
+
+       if (IS_ERR(pcf2127a_device))
+               return PTR_ERR(pcf2127a_device);
+
+       i2c_set_clientdata(client, pcf2127a_device);
+
+       return 0;
+}
+
+/*---------------------------------------------------------------------------*/
+
+static int pcf2127a_remove(struct i2c_client *client)
+{
+       struct rtc_device *pcf2127a_device = i2c_get_clientdata(client);
+
+       if (pcf2127a_device)
+               rtc_device_unregister(pcf2127a_device);
+
+       return 0;
+}
+
+static const struct i2c_device_id pcf2127a_id[] = {
+       /*
+        * This driver should also work with the pcf2127, but
+        * I can't prove it.
+        */
+       { "pcf2127a", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, pcf2127a_id);
+
+static struct i2c_driver pcf2127a_driver = {
+       .driver         = {
+               .name   = "rtc-pcf2127a",
+       },
+       .probe          = pcf2127a_probe,
+       .remove         = pcf2127a_remove,
+       .id_table       = pcf2127a_id,
+};
+
+static int __init pcf2127a_init(void)
+{
+       return i2c_add_driver(&pcf2127a_driver);
+}
+module_init(pcf2127a_init);
+
+static void __exit pcf2127a_exit(void)
+{
+       i2c_del_driver(&pcf2127a_driver);
+}
+module_exit(pcf2127a_exit);
+
+MODULE_AUTHOR("ECKELMANN AG");
+MODULE_DESCRIPTION("NXP/Philips PCF2127A RTC (I2C) driver");
+MODULE_LICENSE("GPL");