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Linux/drivers/spi/spi-octeon.c

  1 /*
  2  * This file is subject to the terms and conditions of the GNU General Public
  3  * License.  See the file "COPYING" in the main directory of this archive
  4  * for more details.
  5  *
  6  * Copyright (C) 2011, 2012 Cavium, Inc.
  7  */
  8 
  9 #include <linux/platform_device.h>
 10 #include <linux/interrupt.h>
 11 #include <linux/spi/spi.h>
 12 #include <linux/module.h>
 13 #include <linux/delay.h>
 14 #include <linux/io.h>
 15 #include <linux/of.h>
 16 
 17 #include <asm/octeon/octeon.h>
 18 #include <asm/octeon/cvmx-mpi-defs.h>
 19 
 20 #define OCTEON_SPI_CFG 0
 21 #define OCTEON_SPI_STS 0x08
 22 #define OCTEON_SPI_TX 0x10
 23 #define OCTEON_SPI_DAT0 0x80
 24 
 25 #define OCTEON_SPI_MAX_BYTES 9
 26 
 27 #define OCTEON_SPI_MAX_CLOCK_HZ 16000000
 28 
 29 struct octeon_spi {
 30         u64 register_base;
 31         u64 last_cfg;
 32         u64 cs_enax;
 33 };
 34 
 35 static void octeon_spi_wait_ready(struct octeon_spi *p)
 36 {
 37         union cvmx_mpi_sts mpi_sts;
 38         unsigned int loops = 0;
 39 
 40         do {
 41                 if (loops++)
 42                         __delay(500);
 43                 mpi_sts.u64 = cvmx_read_csr(p->register_base + OCTEON_SPI_STS);
 44         } while (mpi_sts.s.busy);
 45 }
 46 
 47 static int octeon_spi_do_transfer(struct octeon_spi *p,
 48                                   struct spi_message *msg,
 49                                   struct spi_transfer *xfer,
 50                                   bool last_xfer)
 51 {
 52         struct spi_device *spi = msg->spi;
 53         union cvmx_mpi_cfg mpi_cfg;
 54         union cvmx_mpi_tx mpi_tx;
 55         unsigned int clkdiv;
 56         unsigned int speed_hz;
 57         int mode;
 58         bool cpha, cpol;
 59         const u8 *tx_buf;
 60         u8 *rx_buf;
 61         int len;
 62         int i;
 63 
 64         mode = spi->mode;
 65         cpha = mode & SPI_CPHA;
 66         cpol = mode & SPI_CPOL;
 67 
 68         speed_hz = xfer->speed_hz;
 69 
 70         clkdiv = octeon_get_io_clock_rate() / (2 * speed_hz);
 71 
 72         mpi_cfg.u64 = 0;
 73 
 74         mpi_cfg.s.clkdiv = clkdiv;
 75         mpi_cfg.s.cshi = (mode & SPI_CS_HIGH) ? 1 : 0;
 76         mpi_cfg.s.lsbfirst = (mode & SPI_LSB_FIRST) ? 1 : 0;
 77         mpi_cfg.s.wireor = (mode & SPI_3WIRE) ? 1 : 0;
 78         mpi_cfg.s.idlelo = cpha != cpol;
 79         mpi_cfg.s.cslate = cpha ? 1 : 0;
 80         mpi_cfg.s.enable = 1;
 81 
 82         if (spi->chip_select < 4)
 83                 p->cs_enax |= 1ull << (12 + spi->chip_select);
 84         mpi_cfg.u64 |= p->cs_enax;
 85 
 86         if (mpi_cfg.u64 != p->last_cfg) {
 87                 p->last_cfg = mpi_cfg.u64;
 88                 cvmx_write_csr(p->register_base + OCTEON_SPI_CFG, mpi_cfg.u64);
 89         }
 90         tx_buf = xfer->tx_buf;
 91         rx_buf = xfer->rx_buf;
 92         len = xfer->len;
 93         while (len > OCTEON_SPI_MAX_BYTES) {
 94                 for (i = 0; i < OCTEON_SPI_MAX_BYTES; i++) {
 95                         u8 d;
 96                         if (tx_buf)
 97                                 d = *tx_buf++;
 98                         else
 99                                 d = 0;
100                         cvmx_write_csr(p->register_base + OCTEON_SPI_DAT0 + (8 * i), d);
101                 }
102                 mpi_tx.u64 = 0;
103                 mpi_tx.s.csid = spi->chip_select;
104                 mpi_tx.s.leavecs = 1;
105                 mpi_tx.s.txnum = tx_buf ? OCTEON_SPI_MAX_BYTES : 0;
106                 mpi_tx.s.totnum = OCTEON_SPI_MAX_BYTES;
107                 cvmx_write_csr(p->register_base + OCTEON_SPI_TX, mpi_tx.u64);
108 
109                 octeon_spi_wait_ready(p);
110                 if (rx_buf)
111                         for (i = 0; i < OCTEON_SPI_MAX_BYTES; i++) {
112                                 u64 v = cvmx_read_csr(p->register_base + OCTEON_SPI_DAT0 + (8 * i));
113                                 *rx_buf++ = (u8)v;
114                         }
115                 len -= OCTEON_SPI_MAX_BYTES;
116         }
117 
118         for (i = 0; i < len; i++) {
119                 u8 d;
120                 if (tx_buf)
121                         d = *tx_buf++;
122                 else
123                         d = 0;
124                 cvmx_write_csr(p->register_base + OCTEON_SPI_DAT0 + (8 * i), d);
125         }
126 
127         mpi_tx.u64 = 0;
128         mpi_tx.s.csid = spi->chip_select;
129         if (last_xfer)
130                 mpi_tx.s.leavecs = xfer->cs_change;
131         else
132                 mpi_tx.s.leavecs = !xfer->cs_change;
133         mpi_tx.s.txnum = tx_buf ? len : 0;
134         mpi_tx.s.totnum = len;
135         cvmx_write_csr(p->register_base + OCTEON_SPI_TX, mpi_tx.u64);
136 
137         octeon_spi_wait_ready(p);
138         if (rx_buf)
139                 for (i = 0; i < len; i++) {
140                         u64 v = cvmx_read_csr(p->register_base + OCTEON_SPI_DAT0 + (8 * i));
141                         *rx_buf++ = (u8)v;
142                 }
143 
144         if (xfer->delay_usecs)
145                 udelay(xfer->delay_usecs);
146 
147         return xfer->len;
148 }
149 
150 static int octeon_spi_transfer_one_message(struct spi_master *master,
151                                            struct spi_message *msg)
152 {
153         struct octeon_spi *p = spi_master_get_devdata(master);
154         unsigned int total_len = 0;
155         int status = 0;
156         struct spi_transfer *xfer;
157 
158         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
159                 bool last_xfer = list_is_last(&xfer->transfer_list,
160                                               &msg->transfers);
161                 int r = octeon_spi_do_transfer(p, msg, xfer, last_xfer);
162                 if (r < 0) {
163                         status = r;
164                         goto err;
165                 }
166                 total_len += r;
167         }
168 err:
169         msg->status = status;
170         msg->actual_length = total_len;
171         spi_finalize_current_message(master);
172         return status;
173 }
174 
175 static int octeon_spi_probe(struct platform_device *pdev)
176 {
177         struct resource *res_mem;
178         void __iomem *reg_base;
179         struct spi_master *master;
180         struct octeon_spi *p;
181         int err = -ENOENT;
182 
183         master = spi_alloc_master(&pdev->dev, sizeof(struct octeon_spi));
184         if (!master)
185                 return -ENOMEM;
186         p = spi_master_get_devdata(master);
187         platform_set_drvdata(pdev, master);
188 
189         res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
190         reg_base = devm_ioremap_resource(&pdev->dev, res_mem);
191         if (IS_ERR(reg_base)) {
192                 err = PTR_ERR(reg_base);
193                 goto fail;
194         }
195 
196         p->register_base = (u64)reg_base;
197 
198         master->num_chipselect = 4;
199         master->mode_bits = SPI_CPHA |
200                             SPI_CPOL |
201                             SPI_CS_HIGH |
202                             SPI_LSB_FIRST |
203                             SPI_3WIRE;
204 
205         master->transfer_one_message = octeon_spi_transfer_one_message;
206         master->bits_per_word_mask = SPI_BPW_MASK(8);
207         master->max_speed_hz = OCTEON_SPI_MAX_CLOCK_HZ;
208 
209         master->dev.of_node = pdev->dev.of_node;
210         err = devm_spi_register_master(&pdev->dev, master);
211         if (err) {
212                 dev_err(&pdev->dev, "register master failed: %d\n", err);
213                 goto fail;
214         }
215 
216         dev_info(&pdev->dev, "OCTEON SPI bus driver\n");
217 
218         return 0;
219 fail:
220         spi_master_put(master);
221         return err;
222 }
223 
224 static int octeon_spi_remove(struct platform_device *pdev)
225 {
226         struct spi_master *master = platform_get_drvdata(pdev);
227         struct octeon_spi *p = spi_master_get_devdata(master);
228         u64 register_base = p->register_base;
229 
230         /* Clear the CSENA* and put everything in a known state. */
231         cvmx_write_csr(register_base + OCTEON_SPI_CFG, 0);
232 
233         return 0;
234 }
235 
236 static const struct of_device_id octeon_spi_match[] = {
237         { .compatible = "cavium,octeon-3010-spi", },
238         {},
239 };
240 MODULE_DEVICE_TABLE(of, octeon_spi_match);
241 
242 static struct platform_driver octeon_spi_driver = {
243         .driver = {
244                 .name           = "spi-octeon",
245                 .of_match_table = octeon_spi_match,
246         },
247         .probe          = octeon_spi_probe,
248         .remove         = octeon_spi_remove,
249 };
250 
251 module_platform_driver(octeon_spi_driver);
252 
253 MODULE_DESCRIPTION("Cavium, Inc. OCTEON SPI bus driver");
254 MODULE_AUTHOR("David Daney");
255 MODULE_LICENSE("GPL");
256 

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