linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Lubomir Rintel <lkundrak@v3.sk>
To: Mark Brown <broonie@kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>
Cc: James Cameron <quozl@laptop.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Eric Miao <eric.y.miao@gmail.com>,
	Haojian Zhuang <haojian.zhuang@gmail.com>,
	Daniel Mack <daniel@zonque.org>,
	Robert Jarzmik <robert.jarzmik@free.fr>,
	linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Lubomir Rintel <lkundrak@v3.sk>
Subject: [PATCH v3 5/6] spi: pxa2xx: Add ready signal
Date: Tue, 13 Nov 2018 11:22:27 +0100	[thread overview]
Message-ID: <20181113102228.820214-6-lkundrak@v3.sk> (raw)
In-Reply-To: <20181113102228.820214-1-lkundrak@v3.sk>

Strobe a GPIO line when the slave TX FIFO is filled. This is how the
Embedded Controller on an OLPC XO-1.75 machine, that happens to be a SPI
master, learns that it can initiate a transaction.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Tested-by: Pavel Machek <pavel@ucw.cz>

---
Changes since v2
- Avoid an useless delay if there's no ready GPIO
- Remove useless (int)PTR_ERR(...) casts from pxa2xx_spi_probe()
  (thanks to Geert Uytterhoeven)

 drivers/spi/spi-pxa2xx.c | 16 +++++++++++++++-
 drivers/spi/spi-pxa2xx.h |  3 +++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 54ae77f1227c..7e5aab0af501 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1081,6 +1081,11 @@ static int pxa2xx_spi_transfer_one(struct spi_controller *master,
 	if (spi_controller_is_slave(master)) {
 		while (drv_data->write(drv_data))
 			;
+		if (drv_data->gpiod_ready) {
+			gpiod_set_value(drv_data->gpiod_ready, 1);
+			udelay(1);
+			gpiod_set_value(drv_data->gpiod_ready, 0);
+		}
 	}
 
 	/*
@@ -1778,7 +1783,7 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 				if (PTR_ERR(gpiod) == -ENOENT)
 					continue;
 
-				status = (int)PTR_ERR(gpiod);
+				status = PTR_ERR(gpiod);
 				goto out_error_clock_enabled;
 			} else {
 				drv_data->cs_gpiods[i] = gpiod;
@@ -1786,6 +1791,15 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (platform_info->is_slave) {
+		drv_data->gpiod_ready = devm_gpiod_get_optional(dev,
+						"ready", GPIOD_OUT_LOW);
+		if (IS_ERR(drv_data->gpiod_ready)) {
+			status = PTR_ERR(drv_data->gpiod_ready);
+			goto out_error_clock_enabled;
+		}
+	}
+
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);
diff --git a/drivers/spi/spi-pxa2xx.h b/drivers/spi/spi-pxa2xx.h
index 513c53aaeab2..4e324da66ef7 100644
--- a/drivers/spi/spi-pxa2xx.h
+++ b/drivers/spi/spi-pxa2xx.h
@@ -64,6 +64,9 @@ struct driver_data {
 
 	/* GPIOs for chip selects */
 	struct gpio_desc **cs_gpiods;
+
+	/* Optional slave FIFO ready signal */
+	struct gpio_desc *gpiod_ready;
 };
 
 struct chip_data {
-- 
2.19.1


  parent reply	other threads:[~2018-11-13 10:23 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-13 10:22 [PATCH v3 0/6] spi: pxa2xx: add slave mode support Lubomir Rintel
2018-11-13 10:22 ` [PATCH v3 1/6] spi: pxa2xx: dt-bindings: Add spi-slave property Lubomir Rintel
2018-11-13 10:28   ` Geert Uytterhoeven
2018-11-13 10:22 ` [PATCH v3 2/6] spi: Deal with slaves that return from transfer_one() unfinished Lubomir Rintel
2018-11-13 10:33   ` Geert Uytterhoeven
2018-11-13 18:35   ` Applied "spi: Deal with slaves that return from transfer_one() unfinished" to the spi tree Mark Brown
2018-11-13 10:22 ` [PATCH v3 3/6] spi: pxa2xx: Add slave mode support Lubomir Rintel
2018-11-13 10:22 ` [PATCH v3 4/6] spi: pxa2xx: dt-bindings: Add ready GPIO signal Lubomir Rintel
2018-11-13 10:29   ` Geert Uytterhoeven
2018-11-13 18:34   ` Applied "spi: pxa2xx: dt-bindings: Add ready GPIO signal" to the spi tree Mark Brown
2018-11-13 10:22 ` Lubomir Rintel [this message]
2018-11-13 10:31   ` [PATCH v3 5/6] spi: pxa2xx: Add ready signal Geert Uytterhoeven
2018-11-13 18:34   ` Applied "spi: pxa2xx: Add ready signal" to the spi tree Mark Brown
2018-11-13 10:22 ` [PATCH v3 6/6] spi: pxa2xx: Deal with the leftover garbage in TXFIFO Lubomir Rintel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20181113102228.820214-6-lkundrak@v3.sk \
    --to=lkundrak@v3.sk \
    --cc=broonie@kernel.org \
    --cc=daniel@zonque.org \
    --cc=devicetree@vger.kernel.org \
    --cc=eric.y.miao@gmail.com \
    --cc=geert+renesas@glider.be \
    --cc=haojian.zhuang@gmail.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-spi@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=quozl@laptop.org \
    --cc=robert.jarzmik@free.fr \
    --cc=robh+dt@kernel.org \
    --subject='Re: [PATCH v3 5/6] spi: pxa2xx: Add ready signal' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).