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Date: Tue, 18 Oct 2016 18:08:09 +0200
From: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To: VENKAT PRASHANTH B U <venkat.prashanth2498@...il.com>
Cc: linux-kernel@...r.kernel.org, a.zummo@...ertech.it
Subject: Re: [PATCH] rtc: add support for rtc NXP pca21125
Hi,
Don't forget to Cc the rtc-linux mailing list.
Also, please please run checkpatch on your patches
On 18/10/2016 at 07:47:24 -0700, VENKAT PRASHANTH B U wrote :
> This is the patch to add support for
> NXP rtc pca21125
>
> Signed-off-by: Venkat Prashanth B U <venkat.prashanth2498@...il.com>
> ---
> ---
> drivers/rtc/Kconfig | 12 ++++
> drivers/rtc/Makefile | 1 +
> drivers/rtc/rtc-pca21125.c | 164 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 177 insertions(+)
>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index e215f50..df10e0e 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -686,6 +686,18 @@ config RTC_DRV_MAX6916
> This driver can also be built as a module. If so, the module
> will be called rtc-max6916.
>
> +config RTC_DRV_PCA21125
> + tristate "NXP PCA21125"
> + help
> + If you say yes here you will get support for the
> + NXP PCA21125 SPI RTC chip.
> +
> + This driver only supports the RTC feature, and not other chip
> + features such as alarms.
> +
> + This driver can also be built as a module. If so, the module
> + will be called rtc-pca21125.
> +
> config RTC_DRV_R9701
> tristate "Epson RTC-9701JE"
> help
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 7cf7ad5..2c6af37 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -105,6 +105,7 @@ obj-$(CONFIG_RTC_DRV_NUC900) += rtc-nuc900.o
> obj-$(CONFIG_RTC_DRV_OMAP) += rtc-omap.o
> obj-$(CONFIG_RTC_DRV_OPAL) += rtc-opal.o
> obj-$(CONFIG_RTC_DRV_PALMAS) += rtc-palmas.o
> +obj-$(CONFIG_RTC_DRV_PCA21125) += rtc-pca21125.o
> obj-$(CONFIG_RTC_DRV_PCAP) += rtc-pcap.o
> obj-$(CONFIG_RTC_DRV_PCF2123) += rtc-pcf2123.o
> obj-$(CONFIG_RTC_DRV_PCF2127) += rtc-pcf2127.o
> diff --git a/drivers/rtc/rtc-pca21125.c b/drivers/rtc/rtc-pca21125.c
> index e69de29..8d42e4e 100644
> --- a/drivers/rtc/rtc-pca21125.c
> +++ b/drivers/rtc/rtc-pca21125.c
The whole file is badly indented
> @@ -0,0 +1,164 @@
> + /* rtc-pca21125.c
> + *
> + * Driver for NXP PCA21125 CMOS, SPI Compatible
> + * Real Time Clock
> + *
> + * Author : Venkat Prashanth B U <venkat.prashanth2498@...il.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/init.h>
> + #include <linux/module.h>
> + #include <linux/device.h>
> + #include <linux/platform_device.h>
> + #include <linux/rtc.h>
> + #include <linux/spi/spi.h>
> + #include <linux/bcd.h>
> +
> + /* Registers in pca21125 rtc */
> +
> + #define PCA21125_SECONDS_REG 0x02
> + #define PCA21125_MINUTES_REG 0x03
> + #define PCA21125_HOURS_REG 0x04
> + #define PCA21125_DATE_REG 0x05
> + #define PCA21125_DAY_REG 0x06
> + #define PCA21125_MONTH_REG 0x07
> + #define PCA21125_YEAR_REG 0x08
Those are defined but not used
> + #define PCA21125_CONTROL_REG 0x01
> + #define PCA21125_STATUS_REG 0x00
> + #define PCA21125_CLOCK_BURST 0x0D
> +
> + static int pca21125_read_reg(struct device *dev, unsigned char address,
> + unsigned char *data)
> + {
> + struct spi_device *spi = to_spi_device(dev);
> +
> + *data = address | 0x80;
> +
> + return spi_write_then_read(spi, data, 1, data, 1);
> + }
> +
> + static int pca21125_write_reg(struct device *dev, unsigned char address,
> + unsigned char data)
> + {
> + struct spi_device *spi = to_spi_device(dev);
> + unsigned char buf[2];
> +
> + buf[0] = address & 0x7F;
> + buf[1] = data;
> +
> + return spi_write_then_read(spi, buf, 2, NULL, 0);
> + }
> +
> + static int pca21125_read_time(struct device *dev, struct rtc_time *dt)
> + {
> + struct spi_device *spi = to_spi_device(dev);
> + int err;
> + unsigned char buf[8];
> +
> + buf[0] = PCA21125_CLOCK_BURST | 0x80;
> +
> + err = spi_write_then_read(spi, buf, 1, buf, 8);
> +
> + if (err)
> + return err;
> +
I'm not sure to understand how this can actually work, time/date starts
at 0x2
> + dt->tm_sec = bcd2bin(buf[0]);
> + dt->tm_min = bcd2bin(buf[1]);
> + dt->tm_hour = bcd2bin(buf[2] & 0x3F);
> + dt->tm_mday = bcd2bin(buf[3]);
> + dt->tm_mon = bcd2bin(buf[4]) - 1;
> + dt->tm_wday = bcd2bin(buf[5]) - 1;
> + dt->tm_year = bcd2bin(buf[6]) + 100;
> +
> + return rtc_valid_tm(dt);
> + }
> +
> + static int pca21125_set_time(struct device *dev, struct rtc_time *dt)
> + {
> + struct spi_device *spi = to_spi_device(dev);
> + unsigned char buf[9];
> +
> + if (dt->tm_year < 100 || dt->tm_year > 199) {
> + dev_err(&spi->dev, "Year must be between 2000 and 2099. It's %d.\n",
> + dt->tm_year + 1900);
> + return -EINVAL;
> + }
> +
> + buf[0] = bin2bcd(dt->tm_sec);
> + buf[1] = bin2bcd(dt->tm_min);
> + buf[2] = (bin2bcd(dt->tm_hour) & 0X3F);
> + buf[3] = bin2bcd(dt->tm_mday);
> + buf[4] = bin2bcd(dt->tm_mon + 1);
> + buf[5] = bin2bcd(dt->tm_wday + 1);
> + buf[6] = bin2bcd(dt->tm_year % 100);
> + buf[7] = bin2bcd(0x00);
> +
Isn't it necessary to write the address on the bus first? How does that
work?
> + /* write the rtc settings */
> + return spi_write_then_read(spi, buf, 9, NULL, 0);
> + }
> +
> + static const struct rtc_class_ops pca21125_rtc_ops = {
> + .read_time = pca21125_read_time,
> + .set_time = pca21125_set_time,
> + };
> +
> + static int pca21125_probe(struct spi_device *spi)
> + {
> + struct rtc_device *rtc;
> + unsigned char data;
> + int res;
> +
> + /* spi setup with pca21125 in mode 3 and bits per word as 8 */
> + spi->mode = SPI_MODE_3;
> + spi->bits_per_word = 8;
> + spi_setup(spi);
> +
> + /* RTC Settings */
> + res = pca21125_read_reg(&spi->dev, PCA21125_SECONDS_REG, &data);
> + if (res)
> + return res;
> +
Is that read useful?
> + /* Disable the write protect of rtc */
> + pca21125_read_reg(&spi->dev, PCA21125_CONTROL_REG, &data);
> + data = data & ~(1 << 7);
This is a magic value, please use a define
> + pca21125_write_reg(&spi->dev, PCA21125_CONTROL_REG, data);
> +
> + /*Enable oscillator,disable oscillator stop flag, glitch filter*/
> + pca21125_read_reg(&spi->dev, PCA21125_STATUS_REG, &data);
> + data = data & 0x1B;
ditto
> + pca21125_write_reg(&spi->dev, PCA21125_STATUS_REG, data);
> +
> + /* display the settings */
> + pca21125_read_reg(&spi->dev, PCA21125_CONTROL_REG, &data);
> + dev_info(&spi->dev, "PCA21125 RTC CTRL Reg = 0x%02x\n", data);
> +
I don't think anybody actually cares about that information
> + pca21125_read_reg(&spi->dev, PCA21125_STATUS_REG, &data);
> + dev_info(&spi->dev, "PCA21125 RTC Status Reg = 0x%02x\n", data);
> +
ditto
> + rtc = devm_rtc_device_register(&spi->dev, "pca21125",
> + &pca21125_rtc_ops, THIS_MODULE);
> + if (IS_ERR(rtc))
> + return PTR_ERR(rtc);
> +
> + spi_set_drvdata(spi, rtc);
> +
> + return 0;
> + }
> +
> + static struct spi_driver pca21125_driver = {
> + .driver = {
> + .name = "pca21125",
> + },
> + .probe = pca21125_probe,
> + };
> + module_spi_driver(pca21125_driver);
> +
> + MODULE_DESCRIPTION("PCA21125 SPI RTC DRIVER");
> + MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@...il.com>");
> + MODULE_LICENSE("GPL v2");
> +
> --
> 1.9.2
>
--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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