target/linux/bcm27xx/patches-5.4/950-0134-spi-spi-bcm2835-Re-enable-HW-CS.patch

   1 From 33b150a792ccde6eded4240dea0e3ec784b07d7c Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Tue, 15 Jan 2019 12:39:50 +0000
   4 Subject: [PATCH] spi: spi-bcm2835: Re-enable HW CS
   5
   6 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
   7 ---
   8  drivers/spi/spi-bcm2835.c | 53 +++++++++++++++++++++++++++++++++++++--
   9  1 file changed, 51 insertions(+), 2 deletions(-)
  10
  11 --- a/drivers/spi/spi-bcm2835.c
  12 +++ b/drivers/spi/spi-bcm2835.c
  13 @@ -1169,9 +1169,57 @@ static void bcm2835_spi_handle_err(struc
  14         bcm2835_spi_reset_hw(ctlr);
  15  }
  16
  17 -static int chip_match_name(struct gpio_chip *chip, void *data)
  18 +static void bcm2835_spi_set_cs(struct spi_device *spi, bool gpio_level)
  19  {
  20 -       return !strcmp(chip->label, data);
  21 +       /*
  22 +        * we can assume that we are "native" as per spi_set_cs
  23 +        *   calling us ONLY when cs_gpio is not set
  24 +        * we can also assume that we are CS < 3 as per bcm2835_spi_setup
  25 +        *   we would not get called because of error handling there.
  26 +        * the level passed is the electrical level not enabled/disabled
  27 +        *   so it has to get translated back to enable/disable
  28 +        *   see spi_set_cs in spi.c for the implementation
  29 +        */
  30 +
  31 +       struct spi_master *master = spi->master;
  32 +       struct bcm2835_spi *bs = spi_master_get_devdata(master);
  33 +       u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
  34 +       bool enable;
  35 +
  36 +       /* calculate the enable flag from the passed gpio_level */
  37 +       enable = (spi->mode & SPI_CS_HIGH) ? gpio_level : !gpio_level;
  38 +
  39 +       /* set flags for "reverse" polarity in the registers */
  40 +       if (spi->mode & SPI_CS_HIGH) {
  41 +               /* set the correct CS-bits */
  42 +               cs |= BCM2835_SPI_CS_CSPOL;
  43 +               cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select;
  44 +       } else {
  45 +               /* clean the CS-bits */
  46 +               cs &= ~BCM2835_SPI_CS_CSPOL;
  47 +               cs &= ~(BCM2835_SPI_CS_CSPOL0 << spi->chip_select);
  48 +       }
  49 +
  50 +       /* select the correct chip_select depending on disabled/enabled */
  51 +       if (enable) {
  52 +               /* set cs correctly */
  53 +               if (spi->mode & SPI_NO_CS) {
  54 +                       /* use the "undefined" chip-select */
  55 +                       cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
  56 +               } else {
  57 +                       /* set the chip select */
  58 +                       cs &= ~(BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01);
  59 +                       cs |= spi->chip_select;
  60 +               }
  61 +       } else {
  62 +               /* disable CSPOL which puts HW-CS into deselected state */
  63 +               cs &= ~BCM2835_SPI_CS_CSPOL;
  64 +               /* use the "undefined" chip-select as precaution */
  65 +               cs |= BCM2835_SPI_CS_CS_10 | BCM2835_SPI_CS_CS_01;
  66 +       }
  67 +
  68 +       /* finally set the calculated flags in SPI_CS */
  69 +       bcm2835_wr(bs, BCM2835_SPI_CS, cs);
  70  }
  71
  72  static int bcm2835_spi_setup(struct spi_device *spi)
  73 @@ -1289,6 +1337,7 @@ static int bcm2835_spi_probe(struct plat
  74         ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
  75         ctlr->num_chipselect = BCM2835_SPI_NUM_CS;
  76         ctlr->setup = bcm2835_spi_setup;
  77 +       ctlr->set_cs = bcm2835_spi_set_cs;
  78         ctlr->transfer_one = bcm2835_spi_transfer_one;
  79         ctlr->handle_err = bcm2835_spi_handle_err;
  80         ctlr->prepare_message = bcm2835_spi_prepare_message;