[PATCH v8 02/11] spi: add ti-ssp spi master driver

[Cyril Chemparathy <cyril@ti.com>]

This patch adds an SPI master implementation that operates on top of an
underlying TI-SSP port.

Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Cyril Chemparathy <cyril@ti.com>
---
 drivers/spi/Kconfig        |   10 +
 drivers/spi/Makefile       |    1 +
 drivers/spi/ti-ssp-spi.c   |  402 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/ti_ssp.h |    6 +
 4 files changed, 419 insertions(+), 0 deletions(-)
 create mode 100644 drivers/spi/ti-ssp-spi.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 78f9fd0..7f0ed2a 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -336,6 +336,16 @@ config SPI_TEGRA
 	help
 	  SPI driver for NVidia Tegra SoCs
 
+config SPI_TI_SSP
+	tristate "TI Sequencer Serial Port - SPI Support"
+	depends on MFD_TI_SSP
+	help
+	  This selects an SPI master implementation using a TI sequencer
+	  serial port.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ti-ssp-spi.
+
 config SPI_TOPCLIFF_PCH
 	tristate "Topcliff PCH SPI Controller"
 	depends on PCI
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 8bc1a5a..595e5b8 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_SPI_S3C24XX_GPIO)		+= spi_s3c24xx_gpio.o
 obj-$(CONFIG_SPI_S3C24XX)		+= spi_s3c24xx_hw.o
 obj-$(CONFIG_SPI_S3C64XX)		+= spi_s3c64xx.o
 obj-$(CONFIG_SPI_TEGRA)			+= spi_tegra.o
+obj-$(CONFIG_SPI_TI_SSP)		+= ti-ssp-spi.o
 obj-$(CONFIG_SPI_TOPCLIFF_PCH)		+= spi_topcliff_pch.o
 obj-$(CONFIG_SPI_TXX9)			+= spi_txx9.o
 obj-$(CONFIG_SPI_XILINX)		+= xilinx_spi.o
diff --git a/drivers/spi/ti-ssp-spi.c b/drivers/spi/ti-ssp-spi.c
new file mode 100644
index 0000000..ee22795
--- /dev/null
+++ b/drivers/spi/ti-ssp-spi.c
@@ -0,0 +1,402 @@
+/*
+ * Sequencer Serial Port (SSP) based SPI master driver
+ *
+ * Copyright (C) 2010 Texas Instruments Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/mfd/ti_ssp.h>
+
+#define MODE_BITS	(SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
+
+struct ti_ssp_spi {
+	struct spi_master		*master;
+	struct device			*dev;
+	spinlock_t			lock;
+	struct list_head		msg_queue;
+	struct completion		complete;
+	bool				shutdown;
+	struct workqueue_struct		*workqueue;
+	struct work_struct		work;
+	u8				mode, bpw;
+	int				cs_active;
+	u32				pc_en, pc_dis, pc_wr, pc_rd;
+	void				(*select)(int cs);
+};
+
+static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
+{
+	u32 ret;
+
+	ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
+	return ret;
+}
+
+static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
+{
+	ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
+}
+
+static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
+		       struct spi_transfer *t)
+{
+	int count;
+
+	if (hw->bpw <= 8) {
+		u8		*rx = t->rx_buf;
+		const u8	*tx = t->tx_buf;
+
+		for (count = 0; count < t->len; count += 1) {
+			if (t->tx_buf)
+				ti_ssp_spi_tx(hw, *tx++);
+			if (t->rx_buf)
+				*rx++ = ti_ssp_spi_rx(hw);
+		}
+	} else if (hw->bpw <= 16) {
+		u16		*rx = t->rx_buf;
+		const u16	*tx = t->tx_buf;
+
+		for (count = 0; count < t->len; count += 2) {
+			if (t->tx_buf)
+				ti_ssp_spi_tx(hw, *tx++);
+			if (t->rx_buf)
+				*rx++ = ti_ssp_spi_rx(hw);
+		}
+	} else {
+		u32		*rx = t->rx_buf;
+		const u32	*tx = t->tx_buf;
+
+		for (count = 0; count < t->len; count += 4) {
+			if (t->tx_buf)
+				ti_ssp_spi_tx(hw, *tx++);
+			if (t->rx_buf)
+				*rx++ = ti_ssp_spi_rx(hw);
+		}
+	}
+
+	msg->actual_length += count; /* bytes transferred */
+
+	dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
+		t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
+		hw->bpw, count, (count < t->len) ? " (under)" : "");
+
+	return (count < t->len) ? -EIO : 0; /* left over data */
+}
+
+static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
+{
+	cs_active = !!cs_active;
+	if (cs_active == hw->cs_active)
+		return;
+	ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
+	hw->cs_active = cs_active;
+}
+
+#define __SHIFT_OUT(bits)	(SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
+				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
+#define __SHIFT_IN(bits)	(SSP_OPCODE_SHIFT | SSP_IN_MODE  | \
+				 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
+
+static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
+{
+	int error, idx = 0;
+	u32 seqram[16];
+	u32 cs_en, cs_dis, clk;
+	u32 topbits, botbits;
+
+	mode &= MODE_BITS;
+	if (mode == hw->mode && bpw == hw->bpw)
+		return 0;
+
+	cs_en  = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
+	cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW  : SSP_CS_HIGH;
+	clk    = (mode & SPI_CPOL)    ? SSP_CLK_HIGH : SSP_CLK_LOW;
+
+	/* Construct instructions */
+
+	/* Disable Chip Select */
+	hw->pc_dis = idx;
+	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
+	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_dis | clk;
+
+	/* Enable Chip Select */
+	hw->pc_en = idx;
+	seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
+	seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_en | clk;
+
+	/* Reads and writes need to be split for bpw > 16 */
+	topbits = (bpw > 16) ? 16 : bpw;
+	botbits = bpw - topbits;
+
+	/* Write */
+	hw->pc_wr = idx;
+	seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
+	if (botbits)
+		seqram[idx++] = __SHIFT_OUT(botbits)  | SSP_DATA_REG;
+	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
+
+	/* Read */
+	hw->pc_rd = idx;
+	if (botbits)
+		seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
+	seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
+	seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
+
+	error = ti_ssp_load(hw->dev, 0, seqram, idx);
+	if (error < 0)
+		return error;
+
+	error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
+					  0 : SSP_EARLY_DIN));
+	if (error < 0)
+		return error;
+
+	hw->bpw = bpw;
+	hw->mode = mode;
+
+	return error;
+}
+
+static void ti_ssp_spi_work(struct work_struct *work)
+{
+	struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
+
+	spin_lock(&hw->lock);
+
+	 while (!list_empty(&hw->msg_queue)) {
+		struct spi_message	*m;
+		struct spi_device	*spi;
+		struct spi_transfer	*t = NULL;
+		int			status = 0;
+
+		m = container_of(hw->msg_queue.next, struct spi_message,
+				 queue);
+
+		list_del_init(&m->queue);
+
+		spin_unlock(&hw->lock);
+
+		spi = m->spi;
+
+		if (hw->select)
+			hw->select(spi->chip_select);
+
+		list_for_each_entry(t, &m->transfers, transfer_list) {
+			int bpw = spi->bits_per_word;
+			int xfer_status;
+
+			if (t->bits_per_word)
+				bpw = t->bits_per_word;
+
+			if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
+				break;
+
+			ti_ssp_spi_chip_select(hw, 1);
+
+			xfer_status = ti_ssp_spi_txrx(hw, m, t);
+			if (xfer_status < 0)
+				status = xfer_status;
+
+			if (t->delay_usecs)
+				udelay(t->delay_usecs);
+
+			if (t->cs_change)
+				ti_ssp_spi_chip_select(hw, 0);
+		}
+
+		ti_ssp_spi_chip_select(hw, 0);
+		m->status = status;
+		m->complete(m->context);
+
+		spin_lock(&hw->lock);
+	}
+
+	if (hw->shutdown)
+		complete(&hw->complete);
+
+	spin_unlock(&hw->lock);
+}
+
+static int ti_ssp_spi_setup(struct spi_device *spi)
+{
+	if (spi->bits_per_word > 32)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
+{
+	struct ti_ssp_spi	*hw;
+	struct spi_transfer	*t;
+	int			error = 0;
+
+	m->actual_length = 0;
+	m->status = -EINPROGRESS;
+
+	hw = spi_master_get_devdata(spi->master);
+
+	if (list_empty(&m->transfers) || !m->complete)
+		return -EINVAL;
+
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		if (t->len && !(t->rx_buf || t->tx_buf)) {
+			dev_err(&spi->dev, "invalid xfer, no buffer\n");
+			return -EINVAL;
+		}
+
+		if (t->len && t->rx_buf && t->tx_buf) {
+			dev_err(&spi->dev, "invalid xfer, full duplex\n");
+			return -EINVAL;
+		}
+
+		if (t->bits_per_word > 32) {
+			dev_err(&spi->dev, "invalid xfer width %d\n",
+				t->bits_per_word);
+			return -EINVAL;
+		}
+	}
+
+	spin_lock(&hw->lock);
+	if (hw->shutdown) {
+		error = -ESHUTDOWN;
+		goto error_unlock;
+	}
+	list_add_tail(&m->queue, &hw->msg_queue);
+	queue_work(hw->workqueue, &hw->work);
+error_unlock:
+	spin_unlock(&hw->lock);
+	return error;
+}
+
+static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
+{
+	const struct ti_ssp_spi_data *pdata;
+	struct ti_ssp_spi *hw;
+	struct spi_master *master;
+	struct device *dev = &pdev->dev;
+	int error = 0;
+
+	pdata = dev->platform_data;
+	if (!pdata) {
+		dev_err(dev, "platform data not found\n");
+		return -EINVAL;
+	}
+
+	master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
+	if (!master) {
+		dev_err(dev, "cannot allocate SPI master\n");
+		return -ENOMEM;
+	}
+
+	hw = spi_master_get_devdata(master);
+	platform_set_drvdata(pdev, hw);
+
+	hw->master = master;
+	hw->dev = dev;
+	hw->select = pdata->select;
+
+	spin_lock_init(&hw->lock);
+	init_completion(&hw->complete);
+	INIT_LIST_HEAD(&hw->msg_queue);
+	INIT_WORK(&hw->work, ti_ssp_spi_work);
+
+	hw->workqueue = create_singlethread_workqueue(dev_name(dev));
+	if (!hw->workqueue) {
+		error = -ENOMEM;
+		dev_err(dev, "work queue creation failed\n");
+		goto error_wq;
+	}
+
+	error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
+	if (error < 0) {
+		dev_err(dev, "io setup failed\n");
+		goto error_iosel;
+	}
+
+	master->bus_num		= pdev->id;
+	master->num_chipselect	= pdata->num_cs;
+	master->mode_bits	= MODE_BITS;
+	master->flags		= SPI_MASTER_HALF_DUPLEX;
+	master->setup		= ti_ssp_spi_setup;
+	master->transfer	= ti_ssp_spi_transfer;
+
+	error = spi_register_master(master);
+	if (error) {
+		dev_err(dev, "master registration failed\n");
+		goto error_reg;
+	}
+
+	return 0;
+
+error_reg:
+error_iosel:
+	destroy_workqueue(hw->workqueue);
+error_wq:
+	spi_master_put(master);
+	return error;
+}
+
+static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
+{
+	struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
+	int error;
+
+	hw->shutdown = 1;
+	while (!list_empty(&hw->msg_queue)) {
+		error = wait_for_completion_interruptible(&hw->complete);
+		if (error < 0) {
+			hw->shutdown = 0;
+			return error;
+		}
+	}
+	destroy_workqueue(hw->workqueue);
+	spi_unregister_master(hw->master);
+
+	return 0;
+}
+
+static struct platform_driver ti_ssp_spi_driver = {
+	.probe		= ti_ssp_spi_probe,
+	.remove		= __devexit_p(ti_ssp_spi_remove),
+	.driver		= {
+		.name	= "ti-ssp-spi",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init ti_ssp_spi_init(void)
+{
+	return platform_driver_register(&ti_ssp_spi_driver);
+}
+module_init(ti_ssp_spi_init);
+
+static void __exit ti_ssp_spi_exit(void)
+{
+	platform_driver_unregister(&ti_ssp_spi_driver);
+}
+module_exit(ti_ssp_spi_exit);
+
+MODULE_DESCRIPTION("SSP SPI Master");
+MODULE_AUTHOR("Cyril Chemparathy");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ti-ssp-spi");
diff --git a/include/linux/mfd/ti_ssp.h b/include/linux/mfd/ti_ssp.h
index 021fe09..dbb4b43 100644
--- a/include/linux/mfd/ti_ssp.h
+++ b/include/linux/mfd/ti_ssp.h
@@ -32,6 +32,12 @@ struct ti_ssp_data {
 	struct ti_ssp_dev_data	dev_data[2];
 };
 
+struct ti_ssp_spi_data {
+	unsigned long	iosel;
+	int		num_cs;
+	void		(*select)(int cs);
+};
+
 /*
  * Sequencer port IO pin configuration bits.  These do not correlate 1-1 with
  * the hardware.  The iosel field in the port data combines iosel1 and iosel2,
-- 
1.7.1