linux-kernel - [PATCH 2/2] platform/chrome: cros_ec_spi: Boot fingerprint processor during probe

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Date:   Mon, 14 Mar 2022 16:22:14 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Benson Leung <bleung@...omium.org>
Cc:     linux-kernel@...r.kernel.org, chrome-platform@...ts.linux.dev,
        Guenter Roeck <groeck@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Craig Hesling <hesling@...omium.org>,
        Tom Hughes <tomhughes@...omium.org>,
        Alexandru M Stan <amstan@...omium.org>
Subject: [PATCH 2/2] platform/chrome: cros_ec_spi: Boot fingerprint processor during probe

Add gpio control to this driver so that the fingerprint device can be
booted if the BIOS isn't doing it already. This eases bringup of new
hardware as we don't have to wait for the BIOS to be ready, supports
kexec where the GPIOs may not be configured by the previous boot stage,
and is all around good hygiene because we control GPIOs for this device
from the device driver.

Cc: Guenter Roeck <groeck@...omium.org>
Cc: Douglas Anderson <dianders@...omium.org>
Cc: Craig Hesling <hesling@...omium.org>
Cc: Tom Hughes <tomhughes@...omium.org>
Cc: Alexandru M Stan <amstan@...omium.org>
Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---
 drivers/platform/chrome/cros_ec_spi.c | 38 ++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
index 14c4046fa04d..77577650afce 100644
--- a/drivers/platform/chrome/cros_ec_spi.c
+++ b/drivers/platform/chrome/cros_ec_spi.c
@@ -4,6 +4,7 @@
 // Copyright (C) 2012 Google, Inc
 
 #include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -77,6 +78,8 @@ struct cros_ec_spi {
 	unsigned int start_of_msg_delay;
 	unsigned int end_of_msg_delay;
 	struct kthread_worker *high_pri_worker;
+	struct gpio_desc *boot0;
+	struct gpio_desc *reset;
 };
 
 typedef int (*cros_ec_xfer_fn_t) (struct cros_ec_device *ec_dev,
@@ -690,7 +693,7 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
 	return cros_ec_xfer_high_pri(ec_dev, ec_msg, do_cros_ec_cmd_xfer_spi);
 }
 
-static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
+static int cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
 {
 	struct device_node *np = dev->of_node;
 	u32 val;
@@ -703,6 +706,31 @@ static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
 	ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val);
 	if (!ret)
 		ec_spi->end_of_msg_delay = val;
+
+	if (!of_device_is_compatible(np, "google,cros-ec-fp"))
+		return 0;
+
+	ec_spi->boot0 = devm_gpiod_get(dev, "boot0", 0);
+	if (IS_ERR(ec_spi->boot0))
+		return PTR_ERR(ec_spi->boot0);
+
+	ec_spi->reset = devm_gpiod_get(dev, "reset", 0);
+	if (IS_ERR(ec_spi->reset))
+		return PTR_ERR(ec_spi->reset);
+
+	/*
+	 * Take the FPMCU out of reset and wait for it to boot if it's in
+	 * bootloader mode or held in reset. Otherwise the BIOS has already
+	 * powered on the device earlier in boot in which case there's nothing
+	 * to do.
+	 */
+	if (!gpiod_get_value(ec_spi->boot0) || gpiod_get_value(ec_spi->reset)) {
+		gpiod_set_value(ec_spi->boot0, 1);
+		gpiod_set_value(ec_spi->reset, 0);
+		usleep_range(1000, 2000);
+	}
+
+	return 0;
 }
 
 static void cros_ec_spi_high_pri_release(void *worker)
@@ -754,8 +782,10 @@ static int cros_ec_spi_probe(struct spi_device *spi)
 	if (!ec_dev)
 		return -ENOMEM;
 
-	/* Check for any DT properties */
-	cros_ec_spi_dt_probe(ec_spi, dev);
+	/* Check for any DT properties and boot fpmcu if applicable */
+	err = cros_ec_spi_dt_probe(ec_spi, dev);
+	if (err)
+		return err;
 
 	spi_set_drvdata(spi, ec_dev);
 	ec_dev->dev = dev;
@@ -813,12 +843,14 @@ static SIMPLE_DEV_PM_OPS(cros_ec_spi_pm_ops, cros_ec_spi_suspend,
 			 cros_ec_spi_resume);
 
 static const struct of_device_id cros_ec_spi_of_match[] = {
+	{ .compatible = "google,cros-ec-fp", },
 	{ .compatible = "google,cros-ec-spi", },
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, cros_ec_spi_of_match);
 
 static const struct spi_device_id cros_ec_spi_id[] = {
+	{ "cros-ec-fp", 0 },
 	{ "cros-ec-spi", 0 },
 	{ }
 };
-- 
https://chromeos.dev