nfc: st-nci: Add spi phy support for st21nfcb

st21nfcb does support another phy than i2c: spi.
st21nfcc does not support spi as the spi ios are used
by the AMS RF booster.

st21nfcb is not following NCI NFC Forum recommendations for spi
but rely on ST prioritary protocol ndlc as for i2c.
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/nfc/st-nci/Kconfig

@@ -21,3 +21,14 @@ config NFC_ST_NCI_I2C
 
 	  If you choose to build a module, it'll be called st-nci_i2c.
 	  Say N if unsure.
+
+config NFC_ST_NCI_SPI
+	tristate "NFC ST NCI spi support"
+	depends on NFC_ST_NCI && SPI
+	---help---
+	  This module adds support for an SPI interface to the
+	  STMicroelectronics NFC NCI chips familly.
+	  Select this if your platform is using the spi bus.
+
+	  If you choose to build a module, it'll be called st-nci_spi.
+	  Say N if unsure.

drivers/nfc/st-nci/Makefile

@@ -7,3 +7,6 @@ obj-$(CONFIG_NFC_ST_NCI)     += st-nci.o
 
 st-nci_i2c-objs = i2c.o
 obj-$(CONFIG_NFC_ST_NCI_I2C) += st-nci_i2c.o
+
+st-nci_spi-objs = spi.o
+obj-$(CONFIG_NFC_ST_NCI_SPI) += st-nci_spi.o

drivers/nfc/st-nci/spi.c

+/*
+ * SPI Link Layer for ST NCI based Driver
+ * Copyright (C) 2014-2015 STMicroelectronics SAS. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/gpio.h>
+#include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/nfc.h>
+#include <linux/platform_data/st-nci.h>
+
+#include "ndlc.h"
+
+#define DRIVER_DESC "NCI NFC driver for ST_NCI"
+
+/* ndlc header */
+#define ST_NCI_FRAME_HEADROOM	1
+#define ST_NCI_FRAME_TAILROOM 0
+
+#define ST_NCI_SPI_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
+#define ST_NCI_SPI_MAX_SIZE 250 /* req 4.2.1 */
+
+#define ST_NCI_SPI_DRIVER_NAME "st_nci_spi"
+
+static struct spi_device_id st_nci_spi_id_table[] = {
+	{ST_NCI_SPI_DRIVER_NAME, 0},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, st_nci_spi_id_table);
+
+struct st_nci_spi_phy {
+	struct spi_device *spi_dev;
+	struct llt_ndlc *ndlc;
+
+	unsigned int gpio_reset;
+	unsigned int irq_polarity;
+};
+
+#define SPI_DUMP_SKB(info, skb)					\
+do {								\
+	pr_debug("%s:\n", info);				\
+	print_hex_dump(KERN_DEBUG, "spi: ", DUMP_PREFIX_OFFSET,	\
+		       16, 1, (skb)->data, (skb)->len, 0);	\
+} while (0)
+
+static int st_nci_spi_enable(void *phy_id)
+{
+	struct st_nci_spi_phy *phy = phy_id;
+
+	gpio_set_value(phy->gpio_reset, 0);
+	usleep_range(10000, 15000);
+	gpio_set_value(phy->gpio_reset, 1);
+	usleep_range(80000, 85000);
+
+	if (phy->ndlc->powered == 0)
+		enable_irq(phy->spi_dev->irq);
+
+	return 0;
+}
+
+static void st_nci_spi_disable(void *phy_id)
+{
+	struct st_nci_spi_phy *phy = phy_id;
+
+	disable_irq_nosync(phy->spi_dev->irq);
+}
+
+/*
+ * Writing a frame must not return the number of written bytes.
+ * It must return either zero for success, or <0 for error.
+ * In addition, it must not alter the skb
+ */
+static int st_nci_spi_write(void *phy_id, struct sk_buff *skb)
+{
+	int r;
+	struct st_nci_spi_phy *phy = phy_id;
+	struct spi_device *dev = phy->spi_dev;
+	struct sk_buff *skb_rx;
+	u8 buf[ST_NCI_SPI_MAX_SIZE];
+	struct spi_transfer spi_xfer = {
+		.tx_buf = skb->data,
+		.rx_buf = buf,
+		.len = skb->len,
+	};
+
+	SPI_DUMP_SKB("st_nci_spi_write", skb);
+
+	if (phy->ndlc->hard_fault != 0)
+		return phy->ndlc->hard_fault;
+
+	r = spi_sync_transfer(dev, &spi_xfer, 1);
+	/*
+	 * We may have received some valuable data on miso line.
+	 * Send them back in the ndlc state machine.
+	 */
+	if (!r) {
+		skb_rx = alloc_skb(skb->len, GFP_KERNEL);
+		if (!skb_rx) {
+			r = -ENOMEM;
+			goto exit;
+		}
+
+		skb_put(skb_rx, skb->len);
+		memcpy(skb_rx->data, buf, skb->len);
+		ndlc_recv(phy->ndlc, skb_rx);
+	}
+
+exit:
+	return r;
+}
+
+/*
+ * Reads an ndlc frame and returns it in a newly allocated sk_buff.
+ * returns:
+ * 0 : if received frame is complete
+ * -EREMOTEIO : i2c read error (fatal)
+ * -EBADMSG : frame was incorrect and discarded
+ * -ENOMEM : cannot allocate skb, frame dropped
+ */
+static int st_nci_spi_read(struct st_nci_spi_phy *phy,
+			struct sk_buff **skb)
+{
+	int r;
+	u8 len;
+	u8 buf[ST_NCI_SPI_MAX_SIZE];
+	struct spi_device *dev = phy->spi_dev;
+	struct spi_transfer spi_xfer = {
+		.rx_buf = buf,
+		.len = ST_NCI_SPI_MIN_SIZE,
+	};
+
+	r = spi_sync_transfer(dev, &spi_xfer, 1);
+	if (r < 0)
+		return -EREMOTEIO;
+
+	len = be16_to_cpu(*(__be16 *) (buf + 2));
+	if (len > ST_NCI_SPI_MAX_SIZE) {
+		nfc_err(&dev->dev, "invalid frame len\n");
+		phy->ndlc->hard_fault = 1;
+		return -EBADMSG;
+	}
+
+	*skb = alloc_skb(ST_NCI_SPI_MIN_SIZE + len, GFP_KERNEL);
+	if (*skb == NULL)
+		return -ENOMEM;
+
+	skb_reserve(*skb, ST_NCI_SPI_MIN_SIZE);
+	skb_put(*skb, ST_NCI_SPI_MIN_SIZE);
+	memcpy((*skb)->data, buf, ST_NCI_SPI_MIN_SIZE);
+
+	if (!len)
+		return 0;
+
+	spi_xfer.len = len;
+	r = spi_sync_transfer(dev, &spi_xfer, 1);
+	if (r < 0) {
+		kfree_skb(*skb);
+		return -EREMOTEIO;
+	}
+
+	skb_put(*skb, len);
+	memcpy((*skb)->data + ST_NCI_SPI_MIN_SIZE, buf, len);
+
+	SPI_DUMP_SKB("spi frame read", *skb);
+
+	return 0;
+}
+
+/*
+ * Reads an ndlc frame from the chip.
+ *
+ * On ST21NFCB, IRQ goes in idle state when read starts.
+ */
+static irqreturn_t st_nci_irq_thread_fn(int irq, void *phy_id)
+{
+	struct st_nci_spi_phy *phy = phy_id;
+	struct spi_device *dev;
+	struct sk_buff *skb = NULL;
+	int r;
+
+	if (!phy || !phy->ndlc || irq != phy->spi_dev->irq) {
+		WARN_ON_ONCE(1);
+		return IRQ_NONE;
+	}
+
+	dev = phy->spi_dev;
+	dev_dbg(&dev->dev, "IRQ\n");
+
+	if (phy->ndlc->hard_fault)
+		return IRQ_HANDLED;
+
+	if (!phy->ndlc->powered) {
+		st_nci_spi_disable(phy);
+		return IRQ_HANDLED;
+	}
+
+	r = st_nci_spi_read(phy, &skb);
+	if (r == -EREMOTEIO || r == -ENOMEM || r == -EBADMSG)
+		return IRQ_HANDLED;
+
+	ndlc_recv(phy->ndlc, skb);
+
+	return IRQ_HANDLED;
+}
+
+static struct nfc_phy_ops spi_phy_ops = {
+	.write = st_nci_spi_write,
+	.enable = st_nci_spi_enable,
+	.disable = st_nci_spi_disable,
+};
+
+#ifdef CONFIG_OF
+static int st_nci_spi_of_request_resources(struct spi_device *dev)
+{
+	struct st_nci_spi_phy *phy = spi_get_drvdata(dev);
+	struct device_node *pp;
+	int gpio;
+	int r;
+
+	pp = dev->dev.of_node;
+	if (!pp)
+		return -ENODEV;
+
+	/* Get GPIO from device tree */
+	gpio = of_get_named_gpio(pp, "reset-gpios", 0);
+	if (gpio < 0) {
+		nfc_err(&dev->dev,
+			"Failed to retrieve reset-gpios from device tree\n");
+		return gpio;
+	}
+
+	/* GPIO request and configuration */
+	r = devm_gpio_request_one(&dev->dev, gpio,
+				GPIOF_OUT_INIT_HIGH, "clf_reset");
+	if (r) {
+		nfc_err(&dev->dev, "Failed to request reset pin\n");
+		return r;
+	}
+	phy->gpio_reset = gpio;
+
+	phy->irq_polarity = irq_get_trigger_type(dev->irq);
+
+	return 0;
+}
+#else
+static int st_nci_spi_of_request_resources(struct spi_device *dev)
+{
+	return -ENODEV;
+}
+#endif
+
+static int st_nci_spi_request_resources(struct spi_device *dev)
+{
+	struct st_nci_nfc_platform_data *pdata;
+	struct st_nci_spi_phy *phy = spi_get_drvdata(dev);
+	int r;
+
+	pdata = dev->dev.platform_data;
+	if (pdata == NULL) {
+		nfc_err(&dev->dev, "No platform data\n");
+		return -EINVAL;
+	}
+
+	/* store for later use */
+	phy->gpio_reset = pdata->gpio_reset;
+	phy->irq_polarity = pdata->irq_polarity;
+
+	r = devm_gpio_request_one(&dev->dev,
+			phy->gpio_reset, GPIOF_OUT_INIT_HIGH, "clf_reset");
+	if (r) {
+		pr_err("%s : reset gpio_request failed\n", __FILE__);
+		return r;
+	}
+
+	return 0;
+}
+
+static int st_nci_spi_probe(struct spi_device *dev)
+{
+	struct st_nci_spi_phy *phy;
+	struct st_nci_nfc_platform_data *pdata;
+	int r;
+
+	dev_dbg(&dev->dev, "%s\n", __func__);
+	dev_dbg(&dev->dev, "IRQ: %d\n", dev->irq);
+
+	/* Check SPI platform functionnalities */
+	if (!dev) {
+		pr_debug("%s: dev is NULL. Device is not accessible.\n",
+			__func__);
+		return -ENODEV;
+	}
+
+	phy = devm_kzalloc(&dev->dev, sizeof(struct st_nci_spi_phy),
+			   GFP_KERNEL);
+	if (!phy)
+		return -ENOMEM;
+
+	phy->spi_dev = dev;
+
+	spi_set_drvdata(dev, phy);
+
+	pdata = dev->dev.platform_data;
+	if (!pdata && dev->dev.of_node) {
+		r = st_nci_spi_of_request_resources(dev);
+		if (r) {
+			nfc_err(&dev->dev, "No platform data\n");
+			return r;
+		}
+	} else if (pdata) {
+		r = st_nci_spi_request_resources(dev);
+		if (r) {
+			nfc_err(&dev->dev,
+				"Cannot get platform resources\n");
+			return r;
+		}
+	} else {
+		nfc_err(&dev->dev,
+			"st_nci platform resources not available\n");
+		return -ENODEV;
+	}
+
+	r = ndlc_probe(phy, &spi_phy_ops, &dev->dev,
+			ST_NCI_FRAME_HEADROOM, ST_NCI_FRAME_TAILROOM,
+			&phy->ndlc);
+	if (r < 0) {
+		nfc_err(&dev->dev, "Unable to register ndlc layer\n");
+		return r;
+	}
+
+	r = devm_request_threaded_irq(&dev->dev, dev->irq, NULL,
+				st_nci_irq_thread_fn,
+				phy->irq_polarity | IRQF_ONESHOT,
+				ST_NCI_SPI_DRIVER_NAME, phy);
+	if (r < 0)
+		nfc_err(&dev->dev, "Unable to register IRQ handler\n");
+
+	return r;
+}
+
+static int st_nci_spi_remove(struct spi_device *dev)
+{
+	struct st_nci_spi_phy *phy = spi_get_drvdata(dev);
+
+	dev_dbg(&dev->dev, "%s\n", __func__);
+
+	ndlc_remove(phy->ndlc);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id of_st_nci_spi_match[] = {
+	{ .compatible = "st,st21nfcb-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, of_st_nci_spi_match);
+#endif
+
+static struct spi_driver st_nci_spi_driver = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name = ST_NCI_SPI_DRIVER_NAME,
+		.of_match_table = of_match_ptr(of_st_nci_spi_match),
+	},
+	.probe = st_nci_spi_probe,
+	.id_table = st_nci_spi_id_table,
+	.remove = st_nci_spi_remove,
+};
+
+module_spi_driver(st_nci_spi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION(DRIVER_DESC);