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Subject[PATCH v4 04/12] spi: add ti-ssp spi master driver
Date
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>
---
arch/arm/mach-davinci/include/mach/ti_ssp.h | 5 +
drivers/spi/Kconfig | 7 +
drivers/spi/Makefile | 1 +
drivers/spi/spi_ti_ssp.c | 396 +++++++++++++++++++++++++++
4 files changed, 409 insertions(+), 0 deletions(-)
create mode 100644 drivers/spi/spi_ti_ssp.c

diff --git a/arch/arm/mach-davinci/include/mach/ti_ssp.h b/arch/arm/mach-davinci/include/mach/ti_ssp.h
index c98d0f2..bff8ef6 100644
--- a/arch/arm/mach-davinci/include/mach/ti_ssp.h
+++ b/arch/arm/mach-davinci/include/mach/ti_ssp.h
@@ -34,6 +34,11 @@ struct ti_ssp_data {
struct ti_ssp_dev_data dev_data[2];
};

+struct ti_ssp_spi_data {
+ 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,
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 7e631fa..37b10e3 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -314,6 +314,13 @@ config SPI_STMP3XXX
help
SPI driver for Freescale STMP37xx/378x SoC SSP interface

+config SPI_TI_SSP
+ tristate "TI SSP Controller SPI Driver"
+ depends on TI_SSP
+ help
+ This selects an SPI master implementation using a TI sequencer
+ serial port.
+
config SPI_TXX9
tristate "Toshiba TXx9 SPI controller"
depends on GENERIC_GPIO && CPU_TX49XX
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index e9cbd18..a427f3c 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_SPI_PPC4xx) += spi_ppc4xx.o
obj-$(CONFIG_SPI_S3C24XX_GPIO) += spi_s3c24xx_gpio.o
obj-$(CONFIG_SPI_S3C24XX) += spi_s3c24xx_hw.o
obj-$(CONFIG_SPI_S3C64XX) += spi_s3c64xx.o
+obj-$(CONFIG_SPI_TI_SSP) += spi_ti_ssp.o
obj-$(CONFIG_SPI_TXX9) += spi_txx9.o
obj-$(CONFIG_SPI_XILINX) += xilinx_spi.o
obj-$(CONFIG_SPI_XILINX_OF) += xilinx_spi_of.o
diff --git a/drivers/spi/spi_ti_ssp.c b/drivers/spi/spi_ti_ssp.c
new file mode 100644
index 0000000..3cb41c5
--- /dev/null
+++ b/drivers/spi/spi_ti_ssp.c
@@ -0,0 +1,396 @@
+/*
+ * 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 <mach/ti_ssp.h>
+
+#define MODE_BITS (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
+
+struct ti_ssp_spi {
+ const struct ti_ssp_spi_data *pdata;
+ struct spi_master *master;
+ struct device *dev;
+ spinlock_t lock;
+ struct list_head msg_queue;
+ struct completion complete;
+ int shutdown:1;
+ struct workqueue_struct *workqueue;
+ struct work_struct work;
+ u8 mode, bpw;
+ int cs_active;
+ u32 pc_en, pc_dis, pc_wr, pc_rd;
+};
+
+static u32 do_read_data(struct ti_ssp_spi *hw)
+{
+ u32 ret;
+
+ ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
+ return ret;
+}
+
+static void do_write_data(struct ti_ssp_spi *hw, u32 data)
+{
+ ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
+}
+
+static int do_transfer(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)
+ do_write_data(hw, *tx++);
+ if (t->rx_buf)
+ *rx++ = do_read_data(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)
+ do_write_data(hw, *tx++);
+ if (t->rx_buf)
+ *rx++ = do_read_data(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)
+ do_write_data(hw, *tx++);
+ if (t->rx_buf)
+ *rx++ = do_read_data(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 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 setup_xfer(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->pdata->select)
+ hw->pdata->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 (setup_xfer(hw, bpw, spi->mode) < 0)
+ break;
+
+ chip_select(hw, 1);
+
+ xfer_status = do_transfer(hw, m, t);
+ if (xfer_status < 0)
+ status = xfer_status;
+
+ if (t->delay_usecs)
+ udelay(t->delay_usecs);
+
+ if (t->cs_change)
+ chip_select(hw, 0);
+ }
+
+ 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->pdata = pdata;
+
+ 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;
+ }
+
+ master->bus_num = pdev->id;
+ master->num_chipselect = hw->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:
+ 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);
+}
+subsys_initcall(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:spi_ti_ssp");
--
1.7.0.4


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