caif-driver: Add CAIF-SPI Protocol driver.

This patch introduces the CAIF SPI Protocol Driver for
CAIF Link Layer.

This driver implements a platform driver to accommodate for a
platform specific SPI device. A general platform driver is not
possible as there are no SPI Slave side Kernel API defined.
A sample CAIF SPI Platform device can be found in
.../Documentation/networking/caif/spi_porting.txt

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 252 insertions, 0 deletions

diff --git a/drivers/net/caif/caif_spi_slave.c b/drivers/net/caif/caif_spi_slave.c
new file mode 100644
index 00000000000..077ccf840ed
--- /dev/null
+++ b/drivers/net/caif/caif_spi_slave.c
@@ -0,0 +1,252 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2010
+ * Contact: Sjur Brendeland / sjur.brandeland@stericsson.com
+ * Author:  Daniel Martensson / Daniel.Martensson@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2.
+ */
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/semaphore.h>
+#include <linux/workqueue.h>
+#include <linux/completion.h>
+#include <linux/list.h>
+#include <linux/interrupt.h>
+#include <linux/dma-mapping.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/debugfs.h>
+#include <net/caif/caif_spi.h>
+
+#ifndef CONFIG_CAIF_SPI_SYNC
+#define SPI_DATA_POS SPI_CMD_SZ
+static inline int forward_to_spi_cmd(struct cfspi *cfspi)
+{
+	return cfspi->rx_cpck_len;
+}
+#else
+#define SPI_DATA_POS 0
+static inline int forward_to_spi_cmd(struct cfspi *cfspi)
+{
+	return 0;
+}
+#endif
+
+int spi_frm_align = 2;
+int spi_up_head_align = 1;
+int spi_up_tail_align;
+int spi_down_head_align = 3;
+int spi_down_tail_align = 1;
+
+#ifdef CONFIG_DEBUG_FS
+static inline void debugfs_store_prev(struct cfspi *cfspi)
+{
+	/* Store previous command for debugging reasons.*/
+	cfspi->pcmd = cfspi->cmd;
+	/* Store previous transfer. */
+	cfspi->tx_ppck_len = cfspi->tx_cpck_len;
+	cfspi->rx_ppck_len = cfspi->rx_cpck_len;
+}
+#else
+static inline void debugfs_store_prev(struct cfspi *cfspi)
+{
+}
+#endif
+
+void cfspi_xfer(struct work_struct *work)
+{
+	struct cfspi *cfspi;
+	u8 *ptr = NULL;
+	unsigned long flags;
+	int ret;
+	cfspi = container_of(work, struct cfspi, work);
+
+	/* Initialize state. */
+	cfspi->cmd = SPI_CMD_EOT;
+
+	for (;;) {
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_WAITING);
+
+		/* Wait for master talk or transmit event. */
+		wait_event_interruptible(cfspi->wait,
+				 test_bit(SPI_XFER, &cfspi->state) ||
+				 test_bit(SPI_TERMINATE, &cfspi->state));
+
+		if (test_bit(SPI_TERMINATE, &cfspi->state))
+			return;
+
+#if CFSPI_DBG_PREFILL
+		/* Prefill buffers for easier debugging. */
+		memset(cfspi->xfer.va_tx, 0xFF, SPI_DMA_BUF_LEN);
+		memset(cfspi->xfer.va_rx, 0xFF, SPI_DMA_BUF_LEN);
+#endif	/* CFSPI_DBG_PREFILL */
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_AWAKE);
+
+	/* Check whether we have a committed frame. */
+		if (cfspi->tx_cpck_len) {
+			int len;
+
+			cfspi_dbg_state(cfspi, CFSPI_STATE_FETCH_PKT);
+
+			/* Copy commited SPI frames after the SPI indication. */
+			ptr = (u8 *) cfspi->xfer.va_tx;
+			ptr += SPI_IND_SZ;
+			len = cfspi_xmitfrm(cfspi, ptr, cfspi->tx_cpck_len);
+			WARN_ON(len != cfspi->tx_cpck_len);
+	}
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_GET_NEXT);
+
+		/* Get length of next frame to commit. */
+		cfspi->tx_npck_len = cfspi_xmitlen(cfspi);
+
+		WARN_ON(cfspi->tx_npck_len > SPI_DMA_BUF_LEN);
+
+		/*
+		 * Add indication and length at the beginning of the frame,
+		 * using little endian.
+		 */
+		ptr = (u8 *) cfspi->xfer.va_tx;
+		*ptr++ = SPI_CMD_IND;
+		*ptr++ = (SPI_CMD_IND  & 0xFF00) >> 8;
+		*ptr++ = cfspi->tx_npck_len & 0x00FF;
+		*ptr++ = (cfspi->tx_npck_len & 0xFF00) >> 8;
+
+		/* Calculate length of DMAs. */
+		cfspi->xfer.tx_dma_len = cfspi->tx_cpck_len + SPI_IND_SZ;
+		cfspi->xfer.rx_dma_len = cfspi->rx_cpck_len + SPI_CMD_SZ;
+
+		/* Add SPI TX frame alignment padding, if necessary. */
+		if (cfspi->tx_cpck_len &&
+			(cfspi->xfer.tx_dma_len % spi_frm_align)) {
+
+			cfspi->xfer.tx_dma_len += spi_frm_align -
+			    (cfspi->xfer.tx_dma_len % spi_frm_align);
+		}
+
+		/* Add SPI RX frame alignment padding, if necessary. */
+		if (cfspi->rx_cpck_len &&
+			(cfspi->xfer.rx_dma_len % spi_frm_align)) {
+
+			cfspi->xfer.rx_dma_len += spi_frm_align -
+			    (cfspi->xfer.rx_dma_len % spi_frm_align);
+		}
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_INIT_XFER);
+
+		/* Start transfer. */
+		ret = cfspi->dev->init_xfer(&cfspi->xfer, cfspi->dev);
+		WARN_ON(ret);
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_ACTIVE);
+
+		/*
+		 * TODO: We might be able to make an assumption if this is the
+		 * first loop. Make sure that minimum toggle time is respected.
+		 */
+		udelay(MIN_TRANSITION_TIME_USEC);
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_SIG_ACTIVE);
+
+		/* Signal that we are ready to recieve data. */
+		cfspi->dev->sig_xfer(true, cfspi->dev);
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_XFER_DONE);
+
+		/* Wait for transfer completion. */
+		wait_for_completion(&cfspi->comp);
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_XFER_DONE);
+
+		if (cfspi->cmd == SPI_CMD_EOT) {
+			/*
+			 * Clear the master talk bit. A xfer is always at
+			 *  least two bursts.
+			 */
+			clear_bit(SPI_SS_ON, &cfspi->state);
+		}
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_INACTIVE);
+
+		/* Make sure that the minimum toggle time is respected. */
+		if (SPI_XFER_TIME_USEC(cfspi->xfer.tx_dma_len,
+					cfspi->dev->clk_mhz) <
+			MIN_TRANSITION_TIME_USEC) {
+
+			udelay(MIN_TRANSITION_TIME_USEC -
+				SPI_XFER_TIME_USEC
+				(cfspi->xfer.tx_dma_len, cfspi->dev->clk_mhz));
+		}
+
+		cfspi_dbg_state(cfspi, CFSPI_STATE_SIG_INACTIVE);
+
+		/* De-assert transfer signal. */
+		cfspi->dev->sig_xfer(false, cfspi->dev);
+
+		/* Check whether we received a CAIF packet. */
+		if (cfspi->rx_cpck_len) {
+			int len;
+
+			cfspi_dbg_state(cfspi, CFSPI_STATE_DELIVER_PKT);
+
+			/* Parse SPI frame. */
+			ptr = ((u8 *)(cfspi->xfer.va_rx + SPI_DATA_POS));
+
+			len = cfspi_rxfrm(cfspi, ptr, cfspi->rx_cpck_len);
+			WARN_ON(len != cfspi->rx_cpck_len);
+		}
+
+		/* Check the next SPI command and length. */
+		ptr = (u8 *) cfspi->xfer.va_rx;
+
+		ptr += forward_to_spi_cmd(cfspi);
+
+		cfspi->cmd = *ptr++;
+		cfspi->cmd |= ((*ptr++) << 8) & 0xFF00;
+		cfspi->rx_npck_len = *ptr++;
+		cfspi->rx_npck_len |= ((*ptr++) << 8) & 0xFF00;
+
+		WARN_ON(cfspi->rx_npck_len > SPI_DMA_BUF_LEN);
+		WARN_ON(cfspi->cmd > SPI_CMD_EOT);
+
+		debugfs_store_prev(cfspi);
+
+		/* Check whether the master issued an EOT command. */
+		if (cfspi->cmd == SPI_CMD_EOT) {
+			/* Reset state. */
+			cfspi->tx_cpck_len = 0;
+			cfspi->rx_cpck_len = 0;
+		} else {
+			/* Update state. */
+			cfspi->tx_cpck_len = cfspi->tx_npck_len;
+			cfspi->rx_cpck_len = cfspi->rx_npck_len;
+		}
+
+		/*
+		 * Check whether we need to clear the xfer bit.
+		 * Spin lock needed for packet insertion.
+		 * Test and clear of different bits
+		 * are not supported.
+		 */
+		spin_lock_irqsave(&cfspi->lock, flags);
+		if (cfspi->cmd == SPI_CMD_EOT && !cfspi_xmitlen(cfspi)
+			&& !test_bit(SPI_SS_ON, &cfspi->state))
+			clear_bit(SPI_XFER, &cfspi->state);
+
+		spin_unlock_irqrestore(&cfspi->lock, flags);
+	}
+}
+
+struct platform_driver cfspi_spi_driver = {
+	.probe = cfspi_spi_probe,
+	.remove = cfspi_spi_remove,
+	.driver = {
+		   .name = "cfspi_sspi",
+		   .owner = THIS_MODULE,
+		   },
+};