[PATCH linux v1 1/3] drivers: misc: Platform driver to update display on the POST card

Jaghathiswari Rankappagounder Natarajan jaghu at google.com
Wed Nov 2 05:22:04 AEDT 2016


On Wed, Oct 12, 2016 at 6:09 PM, Rick Altherr <raltherr at google.com> wrote:

>
> On Wed, Oct 12, 2016 at 5:41 PM, Jaghathiswari Rankappagounder Natarajan <
> jaghu at google.com> wrote:
>
>> Platform driver to periodically update the display on the POST card.
>> POST card hardware assumed is 74HC164 wired to two 7-segment displays.
>>
>> Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu at google.com>
>> ---
>>  drivers/misc/Kconfig           |   6 ++
>>  drivers/misc/Makefile          |   1 +
>>  drivers/misc/update-postcard.c | 219 ++++++++++++++++++++++++++++++
>> +++++++++++
>>  drivers/misc/update-postcard.h |   1 +
>>  4 files changed, 227 insertions(+)
>>  create mode 100644 drivers/misc/update-postcard.c
>>  create mode 100644 drivers/misc/update-postcard.h
>>
>> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
>> index 4617ddc..d65b83f 100644
>> --- a/drivers/misc/Kconfig
>> +++ b/drivers/misc/Kconfig
>> @@ -804,6 +804,12 @@ config PANEL_BOOT_MESSAGE
>>           An empty message will only clear the display at driver init
>> time. Any other
>>           printf()-formatted message is valid with newline and escape
>> codes.
>>
>> +config ASPEED_UPDATE_POSTCARD
>> +       tristate "Platform driver to update POST card"
>> +       help
>> +        Support to periodically update display on the POST card. The
>> POST card
>> +        hardware assumed is 74HC164 wired to two 7-segment displays.
>> +
>>
>
> Nothing about this driver is associated with Aspeed.  UPDATE_POSTCARD
> reads to me as describing an action, not a device.  Maybe
> SEVEN_SEGMENT_DISPLAY?
>
>
>>  config ASPEED_BT_IPMI_HOST
>>         tristate "BT IPMI host driver"
>>         help
>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>> index 724861b..730c6c2 100644
>> --- a/drivers/misc/Makefile
>> +++ b/drivers/misc/Makefile
>> @@ -57,4 +57,5 @@ obj-$(CONFIG_ECHO)            += echo/
>>  obj-$(CONFIG_VEXPRESS_SYSCFG)  += vexpress-syscfg.o
>>  obj-$(CONFIG_CXL_BASE)         += cxl/
>>  obj-$(CONFIG_PANEL)             += panel.o
>> +obj-$(CONFIG_ASPEED_UPDATE_POSTCARD)    += update-postcard.o
>>  obj-$(CONFIG_ASPEED_BT_IPMI_HOST)      += bt-host.o
>> diff --git a/drivers/misc/update-postcard.c
>> b/drivers/misc/update-postcard.c
>> new file mode 100644
>> index 0000000..3516c24
>> --- /dev/null
>> +++ b/drivers/misc/update-postcard.c
>> @@ -0,0 +1,219 @@
>> +/* Platform driver to periodically update the display on the POST card.
>> + * POST card hardware assumed is 74HC164 wired to two 7-segment displays.
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/timer.h>
>> +#include <linux/jiffies.h>
>> +#include <linux/sizes.h>
>> +#include <linux/map_to_7segment.h>
>> +#include <linux/io.h>
>> +#include <linux/delay.h>
>> +#include <linux/uaccess.h>
>> +#include <linux/mutex.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/gpio/consumer.h>
>> +
>> +#define POST_CODE_UPDATE_INTVL 1000
>> +
>> +#define MAX_PC_SIZE 3
>> +
>> +#define LED_DOT 0x01
>> +
>> +#define CLOCK_GPIO_NAME "clk"
>> +#define DATA_GPIO_NAME "data"
>> +#define CLEAR_GPIO_NAME "clr"
>> +
>> +static struct mutex mutex;
>> +
>> +static struct timer_list update_timer;
>> +
>> +static char curr_postcode[3];
>> +static u8 pc_valid;
>> +
>>
> +static struct gpio_desc *clk_gpio;
>> +static struct gpio_desc *data_gpio;
>> +static struct gpio_desc *clr_gpio;
>>
>
> I realize there should really only ever be one of these in a system but
> static data members in modules bug me.  I'd much rather see all this
> configuration and these buffers in a struct that is saved with
> platform_set_drvdata().
>
>
>> +
>> +/*
>> + * 0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
>> + *  _       _   _       _   _   _   _   _   _       _       _   _
>> + * | |   |  _|  _| |_| |_  |_    | |_| |_| |_| |_  |    _| |_  |_
>> + * |_|   | |_   _|   |  _| |_|   | |_|   | | | |_| |_  |_| |_  |
>> + *
>> + * data[7:1] = led[a:g]
>> + * lookup table used for both bytes of lpc post code and lower byte of
>> + * bmc post code
>> + */
>> +const u8 seven_seg_bits[] = {
>> +       0xFC, 0x60, 0xDA, 0xF2, 0x66, 0xB6, 0xBE, 0xE0,
>> +       0xFE, 0xF6, 0xEE, 0x3E, 0x9C, 0x7A, 0x9E, 0x8E
>> +       };
>> +
>> +/*
>> + * 0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
>> + *      _       _   _                              _            _
>> + *     |   |_  |_| |_  _   _   _   _   _   _   _  |_    _|  _| | |
>> + *     |_  |_  |   |                               _|  |_| |_| | |
>> + *
>> + * data[7:1] = led[a:g]
>> + * lookup table used for higher byte of bmc post code
>> + */
>> +const u8 special_seven_seg_bits[] = {
>> +       0x00, 0x9C, 0x1E, 0xCE, 0x8E, 0x02, 0x02, 0x02,
>> +       0x02, 0x02, 0x02, 0x02, 0xB6, 0x7A, 0x7A, 0xEC
>> +       };
>> +
>> +void update_postcode(char *buf)
>> +{
>> +       mutex_lock(&mutex);
>> +       strncpy(curr_postcode, buf, sizeof(curr_postcode));
>> +       mutex_unlock(&mutex);
>> +       pc_valid = 1;
>> +}
>> +EXPORT_SYMBOL(update_postcode);
>> +
>> +/* convert postcode to led pattern
>> + * 7-bits used for each 7-seg display and
>> + * 1 bit used for the 'dot' on both digits.
>> + *
>> + *  @param N/A
>> + *  @return N/A
>> + */
>> +static u16 postcode_to_led_signal(void)
>> +{
>> +       u8 low_display;
>> +       u8 high_display;
>> +       u16 led_value;
>> +       char buf[3];
>> +
>> +       mutex_lock(&mutex);
>> +       strncpy(buf, curr_postcode, sizeof(buf));
>> +       mutex_unlock(&mutex);
>> +
>> +       low_display = seven_seg_bits[hex_to_bin(buf[2])];
>> +
>> +       high_display = (buf[0] == '1') ?
>> +               special_seven_seg_bits[hex_to_bin(buf[1])] :
>> +               seven_seg_bits[hex_to_bin(buf[1])];
>> +
>> +       led_value = low_display | (high_display << 8);
>> +       if (buf[0] == '1') {
>> +               led_value |= LED_DOT | (LED_DOT << 8);
>> +       }
>> +
>> +       return led_value;
>> +}
>> +
>> +static void update_sgpio(void)
>> +{
>> +       u16 led_signal;
>> +       int i;
>> +
>> +       /* Convert two bytes of post code to 16 bit led pattern */
>> +       led_signal = postcode_to_led_signal();
>>
>
> Why do you wait until the display update to convert the string to the LED
> bit pattern?  For that matter, why does update_postcode() take a string at
> all?  If you can only display at most a 16-bit number, take a u16 and have
> the caller deal with whatever processing they need.
>
>
>> +
>> +       /* Set the clear signal to low */
>> +       gpiod_set_value(clr_gpio, 0);
>> +       udelay(1);
>> +       /* Set the clear clear to high */
>> +       gpiod_set_value(clr_gpio, 1);
>> +       udelay(1);
>> +
>> +       /* Bitbang the 16 bit led pattern
>> +        * 7-bits used for each 7-seg display
>> +        * 1 bit used for the 'dot' on both digits
>> +        */
>> +       for (i = 0; i < 16; i++) {
>> +               if (led_signal & 0x01) {
>> +                       /* Set the data signal to high */
>> +                       gpiod_set_value(data_gpio, 1);
>> +               } else {
>> +                       /* Set the data signal to low */
>> +                       gpiod_set_value(data_gpio, 0);
>> +               }
>> +               udelay(1);
>> +
>> +               /* Set the clock signal to low */
>> +               gpiod_set_value(clk_gpio, 0);
>> +               udelay(1);
>> +               /* Set the clock signal to high */
>> +               gpiod_set_value(clk_gpio, 1);
>> +               udelay(1);
>> +
>> +               led_signal >>= 1;
>> +       }
>> +}
>> +
>> +static void update_timer_handler(unsigned long data)
>> +{
>> +       if (pc_valid == 1) {
>>
>
> Is this to avoid the time after the driver is register until
> update_postcode() is called the first time?  Is there an API for clearing
> the display?
>
Yes, this is to wait until the user gives a valid display data. I have
included an API for clearing the display in the next patch.


>
>
>> +               update_sgpio();
>> +       }
>> +       mod_timer(&update_timer,
>> +               jiffies + msecs_to_jiffies(POST_CODE_UPDATE_INTVL));
>> +}
>> +
>> +static const struct of_device_id of_postcard_match[] = {
>> +               { .compatible = "postcard-display" },
>> +                       {},
>> +};
>> +
>> +MODULE_DEVICE_TABLE(of, of_postcard_match);
>> +
>> +static int postcard_probe(struct platform_device *pdev)
>> +{
>> +       int result;
>> +       struct device *dev = &pdev->dev;
>> +
>> +       /* Requesting the clock gpio */
>> +       clk_gpio = devm_gpiod_get(dev, CLOCK_GPIO_NAME,
>> +               GPIOD_OUT_HIGH);
>> +       if (IS_ERR(clk_gpio))
>> +               return PTR_ERR(data_gpio);
>> +
>> +       /* Requesting the data gpio */
>> +       data_gpio = devm_gpiod_get(dev, DATA_GPIO_NAME,
>> +               GPIOD_OUT_HIGH);
>> +       if (IS_ERR(data_gpio))
>> +               return PTR_ERR(data_gpio);
>> +
>> +       /* Requesting the clear gpio */
>> +       clr_gpio = devm_gpiod_get(dev, CLEAR_GPIO_NAME,
>> +               GPIOD_OUT_HIGH);
>> +       if (IS_ERR(clr_gpio))
>> +               return PTR_ERR(clr_gpio);
>> +
>> +       /* Start timer to update post code every second */
>> +       setup_timer(&update_timer, update_timer_handler, 0);
>> +       result = mod_timer(&update_timer,
>> +               jiffies + msecs_to_jiffies(POST_CODE_UPDATE_INTVL));
>> +
>> +       if (result)
>> +               return result;
>> +
>> +       mutex_init(&mutex);
>> +
>> +       return 0;
>> +}
>> +
>> +static void postcard_remove(struct platform_device *pdev)
>> +{
>> +       del_timer(&update_timer);
>> +}
>> +
>> +static struct platform_driver postcard_display_driver = {
>> +       .probe          = postcard_probe,
>> +       .shutdown       = postcard_remove,
>> +       .driver         = {
>> +               .name   = "postcard-display",
>> +               .of_match_table = of_postcard_match,
>> +       },
>> +};
>> +
>> +module_platform_driver(postcard_display_driver);
>
> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Jaghathiswari Rankappagounder Natarajan <jaghu at google.com
>> >");
>> +MODULE_DESCRIPTION("Post card display update driver");
>> diff --git a/drivers/misc/update-postcard.h
>> b/drivers/misc/update-postcard.h
>> new file mode 100644
>> index 0000000..ef82e9091d
>> --- /dev/null
>> +++ b/drivers/misc/update-postcard.h
>> @@ -0,0 +1 @@
>> +void update_postcode(char *buf);
>> --
>> 2.8.0.rc3.226.g39d4020
>>
>> _______________________________________________
>> openbmc mailing list
>> openbmc at lists.ozlabs.org
>> https://lists.ozlabs.org/listinfo/openbmc
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ozlabs.org/pipermail/openbmc/attachments/20161101/e937a51e/attachment-0001.html>


More information about the openbmc mailing list