Re: [PATCH RESEND v4] spi/pl022: add devicetree support

From: Rob Herring
Date: Mon Aug 20 2012 - 10:22:44 EST

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@xxxxxxxxx>
> Acked-by: Roland Stigge <stigge@xxxxxxxxx>
> ---
> 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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