Root/drivers/spi/spi-ti-ssp.c

1/*
2 * Sequencer Serial Port (SSP) based SPI master driver
3 *
4 * Copyright (C) 2010 Texas Instruments Inc
5 *
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.
10 *
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.
15 *
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
19 */
20
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>
29
30#define MODE_BITS (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
31
32struct ti_ssp_spi {
33    struct spi_master *master;
34    struct device *dev;
35    spinlock_t lock;
36    struct list_head msg_queue;
37    struct completion complete;
38    bool shutdown;
39    struct workqueue_struct *workqueue;
40    struct work_struct work;
41    u8 mode, bpw;
42    int cs_active;
43    u32 pc_en, pc_dis, pc_wr, pc_rd;
44    void (*select)(int cs);
45};
46
47static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
48{
49    u32 ret;
50
51    ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
52    return ret;
53}
54
55static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
56{
57    ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
58}
59
60static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
61               struct spi_transfer *t)
62{
63    int count;
64
65    if (hw->bpw <= 8) {
66        u8 *rx = t->rx_buf;
67        const u8 *tx = t->tx_buf;
68
69        for (count = 0; count < t->len; count += 1) {
70            if (t->tx_buf)
71                ti_ssp_spi_tx(hw, *tx++);
72            if (t->rx_buf)
73                *rx++ = ti_ssp_spi_rx(hw);
74        }
75    } else if (hw->bpw <= 16) {
76        u16 *rx = t->rx_buf;
77        const u16 *tx = t->tx_buf;
78
79        for (count = 0; count < t->len; count += 2) {
80            if (t->tx_buf)
81                ti_ssp_spi_tx(hw, *tx++);
82            if (t->rx_buf)
83                *rx++ = ti_ssp_spi_rx(hw);
84        }
85    } else {
86        u32 *rx = t->rx_buf;
87        const u32 *tx = t->tx_buf;
88
89        for (count = 0; count < t->len; count += 4) {
90            if (t->tx_buf)
91                ti_ssp_spi_tx(hw, *tx++);
92            if (t->rx_buf)
93                *rx++ = ti_ssp_spi_rx(hw);
94        }
95    }
96
97    msg->actual_length += count; /* bytes transferred */
98
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)" : "");
102
103    return (count < t->len) ? -EIO : 0; /* left over data */
104}
105
106static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
107{
108    cs_active = !!cs_active;
109    if (cs_active == hw->cs_active)
110        return;
111    ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
112    hw->cs_active = cs_active;
113}
114
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))
119
120static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
121{
122    int error, idx = 0;
123    u32 seqram[16];
124    u32 cs_en, cs_dis, clk;
125    u32 topbits, botbits;
126
127    mode &= MODE_BITS;
128    if (mode == hw->mode && bpw == hw->bpw)
129        return 0;
130
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;
134
135    /* Construct instructions */
136
137    /* Disable Chip Select */
138    hw->pc_dis = idx;
139    seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
140    seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_dis | clk;
141
142    /* Enable Chip Select */
143    hw->pc_en = idx;
144    seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
145    seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
146
147    /* Reads and writes need to be split for bpw > 16 */
148    topbits = (bpw > 16) ? 16 : bpw;
149    botbits = bpw - topbits;
150
151    /* Write */
152    hw->pc_wr = idx;
153    seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
154    if (botbits)
155        seqram[idx++] = __SHIFT_OUT(botbits) | SSP_DATA_REG;
156    seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
157
158    /* Read */
159    hw->pc_rd = idx;
160    if (botbits)
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;
164
165    error = ti_ssp_load(hw->dev, 0, seqram, idx);
166    if (error < 0)
167        return error;
168
169    error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
170                      0 : SSP_EARLY_DIN));
171    if (error < 0)
172        return error;
173
174    hw->bpw = bpw;
175    hw->mode = mode;
176
177    return error;
178}
179
180static void ti_ssp_spi_work(struct work_struct *work)
181{
182    struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
183
184    spin_lock(&hw->lock);
185
186     while (!list_empty(&hw->msg_queue)) {
187        struct spi_message *m;
188        struct spi_device *spi;
189        struct spi_transfer *t = NULL;
190        int status = 0;
191
192        m = container_of(hw->msg_queue.next, struct spi_message,
193                 queue);
194
195        list_del_init(&m->queue);
196
197        spin_unlock(&hw->lock);
198
199        spi = m->spi;
200
201        if (hw->select)
202            hw->select(spi->chip_select);
203
204        list_for_each_entry(t, &m->transfers, transfer_list) {
205            int bpw = spi->bits_per_word;
206            int xfer_status;
207
208            if (t->bits_per_word)
209                bpw = t->bits_per_word;
210
211            if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
212                break;
213
214            ti_ssp_spi_chip_select(hw, 1);
215
216            xfer_status = ti_ssp_spi_txrx(hw, m, t);
217            if (xfer_status < 0)
218                status = xfer_status;
219
220            if (t->delay_usecs)
221                udelay(t->delay_usecs);
222
223            if (t->cs_change)
224                ti_ssp_spi_chip_select(hw, 0);
225        }
226
227        ti_ssp_spi_chip_select(hw, 0);
228        m->status = status;
229        m->complete(m->context);
230
231        spin_lock(&hw->lock);
232    }
233
234    if (hw->shutdown)
235        complete(&hw->complete);
236
237    spin_unlock(&hw->lock);
238}
239
240static int ti_ssp_spi_setup(struct spi_device *spi)
241{
242    if (spi->bits_per_word > 32)
243        return -EINVAL;
244
245    return 0;
246}
247
248static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
249{
250    struct ti_ssp_spi *hw;
251    struct spi_transfer *t;
252    int error = 0;
253
254    m->actual_length = 0;
255    m->status = -EINPROGRESS;
256
257    hw = spi_master_get_devdata(spi->master);
258
259    if (list_empty(&m->transfers) || !m->complete)
260        return -EINVAL;
261
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");
265            return -EINVAL;
266        }
267
268        if (t->len && t->rx_buf && t->tx_buf) {
269            dev_err(&spi->dev, "invalid xfer, full duplex\n");
270            return -EINVAL;
271        }
272
273        if (t->bits_per_word > 32) {
274            dev_err(&spi->dev, "invalid xfer width %d\n",
275                t->bits_per_word);
276            return -EINVAL;
277        }
278    }
279
280    spin_lock(&hw->lock);
281    if (hw->shutdown) {
282        error = -ESHUTDOWN;
283        goto error_unlock;
284    }
285    list_add_tail(&m->queue, &hw->msg_queue);
286    queue_work(hw->workqueue, &hw->work);
287error_unlock:
288    spin_unlock(&hw->lock);
289    return error;
290}
291
292static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
293{
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;
298    int error = 0;
299
300    pdata = dev->platform_data;
301    if (!pdata) {
302        dev_err(dev, "platform data not found\n");
303        return -EINVAL;
304    }
305
306    master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
307    if (!master) {
308        dev_err(dev, "cannot allocate SPI master\n");
309        return -ENOMEM;
310    }
311
312    hw = spi_master_get_devdata(master);
313    platform_set_drvdata(pdev, hw);
314
315    hw->master = master;
316    hw->dev = dev;
317    hw->select = pdata->select;
318
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);
323
324    hw->workqueue = create_singlethread_workqueue(dev_name(dev));
325    if (!hw->workqueue) {
326        error = -ENOMEM;
327        dev_err(dev, "work queue creation failed\n");
328        goto error_wq;
329    }
330
331    error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
332    if (error < 0) {
333        dev_err(dev, "io setup failed\n");
334        goto error_iosel;
335    }
336
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;
343
344    error = spi_register_master(master);
345    if (error) {
346        dev_err(dev, "master registration failed\n");
347        goto error_reg;
348    }
349
350    return 0;
351
352error_reg:
353error_iosel:
354    destroy_workqueue(hw->workqueue);
355error_wq:
356    spi_master_put(master);
357    return error;
358}
359
360static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
361{
362    struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
363    int error;
364
365    hw->shutdown = 1;
366    while (!list_empty(&hw->msg_queue)) {
367        error = wait_for_completion_interruptible(&hw->complete);
368        if (error < 0) {
369            hw->shutdown = 0;
370            return error;
371        }
372    }
373    destroy_workqueue(hw->workqueue);
374    spi_unregister_master(hw->master);
375
376    return 0;
377}
378
379static struct platform_driver ti_ssp_spi_driver = {
380    .probe = ti_ssp_spi_probe,
381    .remove = __devexit_p(ti_ssp_spi_remove),
382    .driver = {
383        .name = "ti-ssp-spi",
384        .owner = THIS_MODULE,
385    },
386};
387module_platform_driver(ti_ssp_spi_driver);
388
389MODULE_DESCRIPTION("SSP SPI Master");
390MODULE_AUTHOR("Cyril Chemparathy");
391MODULE_LICENSE("GPL");
392MODULE_ALIAS("platform:ti-ssp-spi");
393

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive