From 4a2b947f56b33cde68d6e0543160ea09ce651fd9 Mon Sep 17 00:00:00 2001
From: Vincent Cuissard <cuissard@marvell.com>
Date: Thu, 11 Jun 2015 11:25:46 +0200
Subject: [PATCH] NFC: nfcmrvl: add chip reset management

Low level driver can specify a GPIO that will be used to reset
the chip. Thanks to this the driver can ensure the state of the
device at init.

Signed-off-by: Vincent Cuissard <cuissard@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
---
 drivers/nfc/nfcmrvl/main.c    | 30 ++++++++++++++++++++++++++++++
 drivers/nfc/nfcmrvl/nfcmrvl.h |  8 ++++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/nfc/nfcmrvl/main.c b/drivers/nfc/nfcmrvl/main.c
index e7f579b2d987..708aad28c567 100644
--- a/drivers/nfc/nfcmrvl/main.c
+++ b/drivers/nfc/nfcmrvl/main.c
@@ -17,6 +17,8 @@
  */
 
 #include <linux/module.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
 #include <linux/nfc.h>
 #include <net/nfc/nci.h>
 #include <net/nfc/nci_core.h>
@@ -107,6 +109,16 @@ struct nfcmrvl_private *nfcmrvl_nci_register_dev(void *drv_data,
 	priv->if_ops = ops;
 	priv->dev = dev;
 	priv->hci_muxed = (flags & NFCMRVL_DEV_FLAG_HCI_MUXED) ? 1 : 0;
+	priv->reset_n_io = NFCMRVL_DEV_FLAG_GET_RESET_N_IO(flags);
+
+	if (priv->reset_n_io) {
+		rc = devm_gpio_request_one(dev,
+					   priv->reset_n_io,
+					   GPIOF_OUT_INIT_LOW,
+					   "nfcmrvl_reset_n");
+		if (rc < 0)
+			nfc_err(dev, "failed to request reset_n io\n");
+	}
 
 	if (priv->hci_muxed)
 		headroom = NFCMRVL_HCI_EVENT_HEADER_SIZE;
@@ -127,6 +139,8 @@ struct nfcmrvl_private *nfcmrvl_nci_register_dev(void *drv_data,
 
 	nci_set_drvdata(priv->ndev, priv);
 
+	nfcmrvl_chip_reset(priv);
+
 	rc = nci_register_device(priv->ndev);
 	if (rc) {
 		nfc_err(dev, "nci_register_device failed %d\n", rc);
@@ -179,6 +193,22 @@ int nfcmrvl_nci_recv_frame(struct nfcmrvl_private *priv, struct sk_buff *skb)
 }
 EXPORT_SYMBOL_GPL(nfcmrvl_nci_recv_frame);
 
+void nfcmrvl_chip_reset(struct nfcmrvl_private *priv)
+{
+	/*
+	 * This function does not take care if someone is using the device.
+	 * To be improved.
+	 */
+
+	if (priv->reset_n_io) {
+		nfc_info(priv->dev, "reset the chip\n");
+		gpio_set_value(priv->reset_n_io, 0);
+		usleep_range(5000, 10000);
+		gpio_set_value(priv->reset_n_io, 1);
+	} else
+		nfc_info(priv->dev, "no reset available on this interface\n");
+}
+
 MODULE_AUTHOR("Marvell International Ltd.");
 MODULE_DESCRIPTION("Marvell NFC driver ver " VERSION);
 MODULE_VERSION(VERSION);
diff --git a/drivers/nfc/nfcmrvl/nfcmrvl.h b/drivers/nfc/nfcmrvl/nfcmrvl.h
index 7a10dabaf1b2..2edae9a4b6bd 100644
--- a/drivers/nfc/nfcmrvl/nfcmrvl.h
+++ b/drivers/nfc/nfcmrvl/nfcmrvl.h
@@ -39,12 +39,18 @@
 #define NFCMRVL_HCI_OCF				0xFE
 
 #define NFCMRVL_DEV_FLAG_HCI_MUXED		(1 << 0)
+#define NFCMRVL_DEV_FLAG_SET_RESET_N_IO(X)	((X) << 16)
+#define NFCMRVL_DEV_FLAG_GET_RESET_N_IO(X)	((X) >> 16)
 
 struct nfcmrvl_private {
 
 	/* Tell if NCI packets are encapsulated in HCI ones */
 	int hci_muxed;
 	struct nci_dev *ndev;
+
+	/* Reset IO (0 if not available) */
+	int reset_n_io;
+
 	unsigned long flags;
 	void *drv_data;
 	struct device *dev;
@@ -63,3 +69,5 @@ struct nfcmrvl_private *nfcmrvl_nci_register_dev(void *drv_data,
 						 struct nfcmrvl_if_ops *ops,
 						 struct device *dev,
 						 unsigned int flags);
+
+void nfcmrvl_chip_reset(struct nfcmrvl_private *priv);