2 * Sequencer Serial Port (SSP) based SPI master driver
4 * Copyright (C) 2010 Texas Instruments Inc
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 #include <linux/kernel.h>
22 #include <linux/err.h>
23 #include <linux/completion.h>
24 #include <linux/delay.h>
25 #include <linux/module.h>
26 #include <linux/platform_device.h>
27 #include <linux/spi/spi.h>
28 #include <linux/mfd/ti_ssp.h>
30 #define MODE_BITS (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
33 struct spi_master *master;
36 struct list_head msg_queue;
37 struct completion complete;
39 struct workqueue_struct *workqueue;
40 struct work_struct work;
43 u32 pc_en, pc_dis, pc_wr, pc_rd;
44 void (*select)(int cs);
47 static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
51 ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
55 static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
57 ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
60 static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
61 struct spi_transfer *t)
67 const u8 *tx = t->tx_buf;
69 for (count = 0; count < t->len; count += 1) {
71 ti_ssp_spi_tx(hw, *tx++);
73 *rx++ = ti_ssp_spi_rx(hw);
75 } else if (hw->bpw <= 16) {
77 const u16 *tx = t->tx_buf;
79 for (count = 0; count < t->len; count += 2) {
81 ti_ssp_spi_tx(hw, *tx++);
83 *rx++ = ti_ssp_spi_rx(hw);
87 const u32 *tx = t->tx_buf;
89 for (count = 0; count < t->len; count += 4) {
91 ti_ssp_spi_tx(hw, *tx++);
93 *rx++ = ti_ssp_spi_rx(hw);
97 msg->actual_length += count; /* bytes transferred */
99 dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
100 t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
101 hw->bpw, count, (count < t->len) ? " (under)" : "");
103 return (count < t->len) ? -EIO : 0; /* left over data */
106 static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
108 cs_active = !!cs_active;
109 if (cs_active == hw->cs_active)
111 ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
112 hw->cs_active = cs_active;
115 #define __SHIFT_OUT(bits) (SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
116 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
117 #define __SHIFT_IN(bits) (SSP_OPCODE_SHIFT | SSP_IN_MODE | \
118 cs_en | clk | SSP_COUNT((bits) * 2 - 1))
120 static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
124 u32 cs_en, cs_dis, clk;
125 u32 topbits, botbits;
128 if (mode == hw->mode && bpw == hw->bpw)
131 cs_en = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
132 cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW : SSP_CS_HIGH;
133 clk = (mode & SPI_CPOL) ? SSP_CLK_HIGH : SSP_CLK_LOW;
135 /* Construct instructions */
137 /* Disable Chip Select */
139 seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
140 seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_dis | clk;
142 /* Enable Chip Select */
144 seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
145 seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
147 /* Reads and writes need to be split for bpw > 16 */
148 topbits = (bpw > 16) ? 16 : bpw;
149 botbits = bpw - topbits;
153 seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
155 seqram[idx++] = __SHIFT_OUT(botbits) | SSP_DATA_REG;
156 seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
161 seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
162 seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
163 seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
165 error = ti_ssp_load(hw->dev, 0, seqram, idx);
169 error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
180 static void ti_ssp_spi_work(struct work_struct *work)
182 struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
184 spin_lock(&hw->lock);
186 while (!list_empty(&hw->msg_queue)) {
187 struct spi_message *m;
188 struct spi_device *spi;
189 struct spi_transfer *t = NULL;
192 m = container_of(hw->msg_queue.next, struct spi_message,
195 list_del_init(&m->queue);
197 spin_unlock(&hw->lock);
202 hw->select(spi->chip_select);
204 list_for_each_entry(t, &m->transfers, transfer_list) {
205 int bpw = spi->bits_per_word;
208 if (t->bits_per_word)
209 bpw = t->bits_per_word;
211 if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
214 ti_ssp_spi_chip_select(hw, 1);
216 xfer_status = ti_ssp_spi_txrx(hw, m, t);
218 status = xfer_status;
221 udelay(t->delay_usecs);
224 ti_ssp_spi_chip_select(hw, 0);
227 ti_ssp_spi_chip_select(hw, 0);
229 m->complete(m->context);
231 spin_lock(&hw->lock);
235 complete(&hw->complete);
237 spin_unlock(&hw->lock);
240 static int ti_ssp_spi_setup(struct spi_device *spi)
242 if (spi->bits_per_word > 32)
248 static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
250 struct ti_ssp_spi *hw;
251 struct spi_transfer *t;
254 m->actual_length = 0;
255 m->status = -EINPROGRESS;
257 hw = spi_master_get_devdata(spi->master);
259 if (list_empty(&m->transfers) || !m->complete)
262 list_for_each_entry(t, &m->transfers, transfer_list) {
263 if (t->len && !(t->rx_buf || t->tx_buf)) {
264 dev_err(&spi->dev, "invalid xfer, no buffer\n");
268 if (t->len && t->rx_buf && t->tx_buf) {
269 dev_err(&spi->dev, "invalid xfer, full duplex\n");
273 if (t->bits_per_word > 32) {
274 dev_err(&spi->dev, "invalid xfer width %d\n",
280 spin_lock(&hw->lock);
285 list_add_tail(&m->queue, &hw->msg_queue);
286 queue_work(hw->workqueue, &hw->work);
288 spin_unlock(&hw->lock);
292 static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
294 const struct ti_ssp_spi_data *pdata;
295 struct ti_ssp_spi *hw;
296 struct spi_master *master;
297 struct device *dev = &pdev->dev;
300 pdata = dev->platform_data;
302 dev_err(dev, "platform data not found\n");
306 master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
308 dev_err(dev, "cannot allocate SPI master\n");
312 hw = spi_master_get_devdata(master);
313 platform_set_drvdata(pdev, hw);
317 hw->select = pdata->select;
319 spin_lock_init(&hw->lock);
320 init_completion(&hw->complete);
321 INIT_LIST_HEAD(&hw->msg_queue);
322 INIT_WORK(&hw->work, ti_ssp_spi_work);
324 hw->workqueue = create_singlethread_workqueue(dev_name(dev));
325 if (!hw->workqueue) {
327 dev_err(dev, "work queue creation failed\n");
331 error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
333 dev_err(dev, "io setup failed\n");
337 master->bus_num = pdev->id;
338 master->num_chipselect = pdata->num_cs;
339 master->mode_bits = MODE_BITS;
340 master->flags = SPI_MASTER_HALF_DUPLEX;
341 master->setup = ti_ssp_spi_setup;
342 master->transfer = ti_ssp_spi_transfer;
344 error = spi_register_master(master);
346 dev_err(dev, "master registration failed\n");
354 destroy_workqueue(hw->workqueue);
356 spi_master_put(master);
360 static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
362 struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
366 while (!list_empty(&hw->msg_queue)) {
367 error = wait_for_completion_interruptible(&hw->complete);
373 destroy_workqueue(hw->workqueue);
374 spi_unregister_master(hw->master);
379 static struct platform_driver ti_ssp_spi_driver = {
380 .probe = ti_ssp_spi_probe,
381 .remove = __devexit_p(ti_ssp_spi_remove),
383 .name = "ti-ssp-spi",
384 .owner = THIS_MODULE,
387 module_platform_driver(ti_ssp_spi_driver);
389 MODULE_DESCRIPTION("SSP SPI Master");
390 MODULE_AUTHOR("Cyril Chemparathy");
391 MODULE_LICENSE("GPL");
392 MODULE_ALIAS("platform:ti-ssp-spi");