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    SubjectRe: [PATCH RESEND v4] spi/pl022: add devicetree support
    On 08/20/2012 06:39 AM, Alexandre Pereira da Silva wrote:
    > Add the chipselect array and cur_cs properties to pl022 main structure
    >
    > Add a wrapper function to decide if the cs should be controlled by the
    > cs_control callback or the chipselect gpio
    >
    > Populate chipselect property from cs-gpios
    >
    > Populate master->dev.of_node, so the spi bus can find child spi
    > devices and register them
    >
    > At pl022 setup, fill chip_data structure from dt nodes, if not provided
    > by platform.
    >
    > Signed-off-by: Alexandre Pereira da Silva <aletes.xgr@gmail.com>
    > Acked-by: Roland Stigge <stigge@antcom.de>
    > ---
    > Applies to v3.6-rc1
    >
    > Changes since v3:
    > * Proper use of IS_ENABLED
    >
    > Changes since v2:
    > * Use IS_ENABLED instead of #ifdef
    > * Remove bogus const change
    >
    > Changes since v1:
    > * return EPROBE_DEFFER if gpios are not initialized yet
    >
    > Thanks Thierry Reding for reviewing and improvements suggestions
    >
    > .../devicetree/bindings/spi/spi_pl022.txt | 15 +++
    > drivers/spi/spi-pl022.c | 114 ++++++++++++++++----
    > 2 files changed, 110 insertions(+), 19 deletions(-)
    >
    > diff --git a/Documentation/devicetree/bindings/spi/spi_pl022.txt b/Documentation/devicetree/bindings/spi/spi_pl022.txt
    > index 306ec3f..b089ec7 100644
    > --- a/Documentation/devicetree/bindings/spi/spi_pl022.txt
    > +++ b/Documentation/devicetree/bindings/spi/spi_pl022.txt
    > @@ -6,7 +6,22 @@ Required properties:
    > - interrupts : Should contain SPI controller interrupt
    >
    > Optional properties:
    > +- pl022,num-chipselects : total number of chipselects

    We have this for other spi controllers too. Define a generic property.

    > - cs-gpios : should specify GPIOs used for chipselects.
    > The gpios will be referred to as reg = <index> in the SPI child nodes.
    > If unspecified, a single SPI device without a chip select can be used.
    >
    > +SPI slave nodes must be children of the SPI master node and can
    > +contain the following properties.
    > +See include/linux/amba/pl022.h for more details

    DT binding is independent of Linux, so you should not refer to Linux docs.

    > +
    > +- pl022,hierarchy : master or slave interface

    Is attaching a master and using the pl022 as a slave really a supported
    use case? The DT spi bindings are really designed for a master node with
    N slave nodes. So there is more general question of how to describe a
    spi controller as a slave. It's not really one I care to answer as the
    Linux spi framework isn't designed to act as a slave.

    > +- pl022,interface : interface type

    And valid values are?

    > +- pl022,slave-tx-disable : disconnect tx line in slave mode
    > +- pl022,com-mode : polling, interrupt or dma
    > +- pl022,rx-level-trig : Rx FIFO watermark level
    > +- pl022,tx-level-trig : Tx FIFO watermark level
    > +- pl022,ctrl-len : Microwire interface: Control length
    > +- pl022,wait-state : Microwire interface: Wait state
    > +- pl022,duplex : Microwire interface: Full/Half duplex

    Most of these properties aren't used anywhere in the kernel other than
    u300 and I'm not sure what to purpose of dummy_chip_info is. Perhaps
    Linus has some input? I think either they can be decided by the spi
    controller (com-mode, fifo watermark) or should be standard properties
    (microwire settings). I would argue they should be removed if the spi
    framework doesn't have support in a standard way.

    > +
    > diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
    > index 400ae21..d8d7d21 100644
    > --- a/drivers/spi/spi-pl022.c
    > +++ b/drivers/spi/spi-pl022.c
    > @@ -40,6 +40,8 @@
    > #include <linux/dma-mapping.h>
    > #include <linux/scatterlist.h>
    > #include <linux/pm_runtime.h>
    > +#include <linux/gpio.h>
    > +#include <linux/of_gpio.h>
    >
    > /*
    > * This macro is used to define some register default values.
    > @@ -389,6 +391,8 @@ struct pl022 {
    > char *dummypage;
    > bool dma_running;
    > #endif
    > + int cur_cs;
    > + int chipselect[0];
    > };
    >
    > /**
    > @@ -433,6 +437,14 @@ static void null_cs_control(u32 command)
    > pr_debug("pl022: dummy chip select control, CS=0x%x\n", command);
    > }
    >
    > +static void pl022_cs_control(struct pl022 *pl022, u32 command)
    > +{
    > + if (gpio_is_valid(pl022->cur_cs))
    > + gpio_set_value(pl022->cur_cs, command);
    > + else
    > + pl022->cur_chip->cs_control(command);
    > +}
    > +
    > /**
    > * giveback - current spi_message is over, schedule next message and call
    > * callback of this message. Assumes that caller already
    > @@ -479,7 +491,7 @@ static void giveback(struct pl022 *pl022)
    > if (next_msg && next_msg->spi != pl022->cur_msg->spi)
    > next_msg = NULL;
    > if (!next_msg || pl022->cur_msg->state == STATE_ERROR)
    > - pl022->cur_chip->cs_control(SSP_CHIP_DESELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_DESELECT);
    > else
    > pl022->next_msg_cs_active = true;
    >
    > @@ -813,8 +825,7 @@ static void dma_callback(void *data)
    > /* Update total bytes transferred */
    > msg->actual_length += pl022->cur_transfer->len;
    > if (pl022->cur_transfer->cs_change)
    > - pl022->cur_chip->
    > - cs_control(SSP_CHIP_DESELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_DESELECT);
    >
    > /* Move to next transfer */
    > msg->state = next_transfer(pl022);
    > @@ -1247,8 +1258,7 @@ static irqreturn_t pl022_interrupt_handler(int irq, void *dev_id)
    > /* Update total bytes transferred */
    > msg->actual_length += pl022->cur_transfer->len;
    > if (pl022->cur_transfer->cs_change)
    > - pl022->cur_chip->
    > - cs_control(SSP_CHIP_DESELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_DESELECT);
    > /* Move to next transfer */
    > msg->state = next_transfer(pl022);
    > tasklet_schedule(&pl022->pump_transfers);
    > @@ -1333,7 +1343,7 @@ static void pump_transfers(unsigned long data)
    >
    > /* Reselect chip select only if cs_change was requested */
    > if (previous->cs_change)
    > - pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_SELECT);
    > } else {
    > /* STATE_START */
    > message->state = STATE_RUNNING;
    > @@ -1372,7 +1382,7 @@ static void do_interrupt_dma_transfer(struct pl022 *pl022)
    >
    > /* Enable target chip, if not already active */
    > if (!pl022->next_msg_cs_active)
    > - pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_SELECT);
    >
    > if (set_up_next_transfer(pl022, pl022->cur_transfer)) {
    > /* Error path */
    > @@ -1424,12 +1434,12 @@ static void do_polling_transfer(struct pl022 *pl022)
    > if (previous->delay_usecs)
    > udelay(previous->delay_usecs);
    > if (previous->cs_change)
    > - pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_SELECT);
    > } else {
    > /* STATE_START */
    > message->state = STATE_RUNNING;
    > if (!pl022->next_msg_cs_active)
    > - pl022->cur_chip->cs_control(SSP_CHIP_SELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_SELECT);
    > }
    >
    > /* Configuration Changing Per Transfer */
    > @@ -1461,7 +1471,7 @@ static void do_polling_transfer(struct pl022 *pl022)
    > /* Update total byte transferred */
    > message->actual_length += pl022->cur_transfer->len;
    > if (pl022->cur_transfer->cs_change)
    > - pl022->cur_chip->cs_control(SSP_CHIP_DESELECT);
    > + pl022_cs_control(pl022, SSP_CHIP_DESELECT);
    > /* Move to next transfer */
    > message->state = next_transfer(pl022);
    > }
    > @@ -1490,6 +1500,7 @@ static int pl022_transfer_one_message(struct spi_master *master,
    >
    > /* Setup the SPI using the per chip configuration */
    > pl022->cur_chip = spi_get_ctldata(msg->spi);
    > + pl022->cur_cs = pl022->chipselect[msg->spi->chip_select];
    >
    > restore_state(pl022);
    > flush(pl022);
    > @@ -1761,12 +1772,14 @@ static const struct pl022_config_chip pl022_default_chip_info = {
    > static int pl022_setup(struct spi_device *spi)
    > {
    > struct pl022_config_chip const *chip_info;
    > + struct pl022_config_chip chip_info_dt;
    > struct chip_data *chip;
    > struct ssp_clock_params clk_freq = { .cpsdvsr = 0, .scr = 0};
    > int status = 0;
    > struct pl022 *pl022 = spi_master_get_devdata(spi->master);
    > unsigned int bits = spi->bits_per_word;
    > u32 tmp;
    > + struct device_node *np = spi->dev.of_node;
    >
    > if (!spi->max_speed_hz)
    > return -EINVAL;
    > @@ -1789,10 +1802,36 @@ static int pl022_setup(struct spi_device *spi)
    > chip_info = spi->controller_data;
    >
    > if (chip_info == NULL) {
    > - chip_info = &pl022_default_chip_info;
    > - /* spi_board_info.controller_data not is supplied */
    > - dev_dbg(&spi->dev,
    > - "using default controller_data settings\n");
    > + if (np) {
    > + chip_info_dt = pl022_default_chip_info;
    > +
    > + of_property_read_u32(np, "pl022,hierarchy",
    > + &chip_info_dt.hierarchy);
    > + of_property_read_u32(np, "pl022,interface",
    > + &chip_info_dt.iface);
    > + chip_info_dt.slave_tx_disable =
    > + of_property_read_bool(np,
    > + "pl022,slave-tx-disable");
    > + of_property_read_u32(np, "pl022,com-mode",
    > + &chip_info_dt.com_mode);
    > + of_property_read_u32(np, "pl022,rx-level-trig",
    > + &chip_info_dt.rx_lev_trig);
    > + of_property_read_u32(np, "pl022,tx-level-trig",
    > + &chip_info_dt.tx_lev_trig);
    > + of_property_read_u32(np, "pl022,ctrl-len",
    > + &chip_info_dt.ctrl_len);
    > + of_property_read_u32(np, "pl022,wait-state",
    > + &chip_info_dt.wait_state);
    > + of_property_read_u32(np, "pl022,duplex",
    > + &chip_info_dt.duplex);
    > +
    > + chip_info = &chip_info_dt;
    > + } else {
    > + chip_info = &pl022_default_chip_info;
    > + /* spi_board_info.controller_data not is supplied */
    > + dev_dbg(&spi->dev,
    > + "using default controller_data settings\n");
    > + }
    > } else
    > dev_dbg(&spi->dev,
    > "using user supplied controller_data settings\n");
    > @@ -1835,8 +1874,9 @@ static int pl022_setup(struct spi_device *spi)
    > chip->xfer_type = chip_info->com_mode;
    > if (!chip_info->cs_control) {
    > chip->cs_control = null_cs_control;
    > - dev_warn(&spi->dev,
    > - "chip select function is NULL for this chip\n");
    > + if (!gpio_is_valid(pl022->chipselect[spi->chip_select]))
    > + dev_warn(&spi->dev,
    > + "chip select function is NULL for this chip\n");
    > } else
    > chip->cs_control = chip_info->cs_control;
    >
    > @@ -1988,7 +2028,8 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
    > struct pl022_ssp_controller *platform_info = adev->dev.platform_data;
    > struct spi_master *master;
    > struct pl022 *pl022 = NULL; /*Data for this driver */
    > - int status = 0;
    > + struct device_node *np = adev->dev.of_node;
    > + int status = 0, i, num_cs;
    >
    > dev_info(&adev->dev,
    > "ARM PL022 driver, device ID: 0x%08x\n", adev->periphid);
    > @@ -1998,8 +2039,14 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
    > goto err_no_pdata;
    > }
    >
    > + num_cs = platform_info->num_chipselect;
    > + if (IS_ENABLED(CONFIG_OF))
    > + of_property_read_u32(np, "pl022,num-chipselects", &num_cs);
    > +
    > +
    > /* Allocate master with space for data */
    > - master = spi_alloc_master(dev, sizeof(struct pl022));
    > + master = spi_alloc_master(dev,
    > + sizeof(struct pl022) + sizeof(int) * num_cs);
    > if (master == NULL) {
    > dev_err(&adev->dev, "probe - cannot alloc SPI master\n");
    > status = -ENOMEM;
    > @@ -2017,13 +2064,41 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
    > * on this board
    > */
    > master->bus_num = platform_info->bus_id;
    > - master->num_chipselect = platform_info->num_chipselect;
    > + master->num_chipselect = num_cs;
    > master->cleanup = pl022_cleanup;
    > master->setup = pl022_setup;
    > master->prepare_transfer_hardware = pl022_prepare_transfer_hardware;
    > master->transfer_one_message = pl022_transfer_one_message;
    > master->unprepare_transfer_hardware = pl022_unprepare_transfer_hardware;
    > master->rt = platform_info->rt;
    > + master->dev.of_node = dev->of_node;
    > +
    > + if (IS_ENABLED(CONFIG_OF)) {
    > + for (i = 0; i < num_cs; i++) {
    > + int cs_gpio = of_get_named_gpio(np, "cs-gpios", i);
    > +
    > + if (cs_gpio == -EPROBE_DEFER) {
    > + status = -EPROBE_DEFER;
    > + goto err_no_gpio;
    > + }
    > +
    > + pl022->chipselect[i] = cs_gpio;
    > +
    > + if (gpio_is_valid(cs_gpio)) {
    > + if (gpio_request(cs_gpio, "ssp-pl022"))
    > + dev_err(&adev->dev,
    > + "could not request %d gpio\n",
    > + cs_gpio);
    > + else if (gpio_direction_output(cs_gpio, 1))
    > + dev_err(&adev->dev,
    > + "could set gpio %d as output\n",
    > + cs_gpio);
    > + }
    > + }
    > + } else {
    > + for (i = 0; i < num_cs; i++)
    > + pl022->chipselect[i] = -EINVAL;
    > + }
    >
    > /*
    > * Supports mode 0-3, loopback, and active low CS. Transfers are
    > @@ -2130,6 +2205,7 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
    > err_no_ioremap:
    > amba_release_regions(adev);
    > err_no_ioregion:
    > + err_no_gpio:
    > spi_master_put(master);
    > err_no_master:
    > err_no_pdata:
    >


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