4 * This file is part of BeRTOS.
6 * Bertos 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2010 Develer S.r.l. (http://www.develer.com/)
33 * \brief LM3S1968 Synchronous Serial Interface (SSI) driver.
35 * \author Andrea Righi <arighi@develer.com>
38 #include <cfg/compiler.h>
39 #include <cfg/debug.h>
40 #include <string.h> /* memset() */
43 /* SSI clocking informations (CPSDVSR + SCR) */
51 * Evaluate the SSI clock prescale (SSICPSR) and SSI serial clock rate (SCR).
53 INLINE struct SSIClock
54 lm3s_ssiPrescale(unsigned int bitrate)
58 for (ret.cpsdvsr = 2, ret.scr = CPU_FREQ / bitrate / ret.cpsdvsr - 1;
59 ret.scr > 255; ret.cpsdvsr += 2);
60 ASSERT(ret.cpsdvsr < 255);
66 * Initialize the SSI interface.
68 * Return 0 in case of success, a negative value otherwise.
70 int lm3s_ssiOpen(uint32_t addr, uint32_t frame, int mode,
71 int bitrate, uint32_t data_width)
73 struct SSIClock ssi_clock;
75 ASSERT(addr == SSI0_BASE || addr == SSI1_BASE);
76 /* Configure the SSI operating mode */
79 /* SSI Slave Mode Output Disable */
80 case SSI_MODE_SLAVE_OD:
81 HWREG(addr + SSI_O_CR1) = SSI_CR1_SOD;
85 HWREG(addr + SSI_O_CR1) = SSI_CR1_MS;
89 HWREG(addr + SSI_O_CR1) = 0;
95 /* Configure the peripheral clock and frame format */
96 ssi_clock = lm3s_ssiPrescale(bitrate);
97 HWREG(addr + SSI_O_CPSR) = ssi_clock.cpsdvsr;
98 HWREG(addr + SSI_O_CR0) =
99 (ssi_clock.scr << 8) |
101 (frame & SSI_CR0_FRF_M) |
103 /* Enable the SSI interface */
104 HWREG(addr + SSI_O_CR1) |= SSI_CR1_SSE;
110 * Write data to the SSI bus.
112 * Return the number of bytes written to the bus.
114 static size_t lm3s_ssiWrite(struct KFile *fd, const void *buf, size_t size)
116 LM3SSSI *fds = LM3SSSI_CAST(fd);
117 const char *p = (const char *)buf;
124 if (fds->flags & LM3S_SSI_NONBLOCK)
126 if (!lm3s_ssiWriteFrameNonBlocking(fds->addr,
131 lm3s_ssiWriteFrame(fds->addr, frame);
138 * Read data from the SSI bus.
140 * Return the number of bytes read from the bus.
142 static size_t lm3s_ssiRead(struct KFile *fd, void *buf, size_t size)
144 LM3SSSI *fds = LM3SSSI_CAST(fd);
146 uint8_t *p = (uint8_t *)buf;
152 if (fds->flags & LM3S_SSI_NONBLOCK)
154 if (!lm3s_ssiReadFrameNonBlocking(fds->addr, &frame))
158 lm3s_ssiReadFrame(fds->addr, &frame);
159 *p++ = (uint8_t)frame;
166 /* Wait for data in the TX FIFO being actually transmitted */
167 static int lm3s_ssiFlush(struct KFile *fd)
169 LM3SSSI *fds = LM3SSSI_CAST(fd);
171 while (!lm3s_ssiTxDone(fds->addr))
176 /* Disable the SSI interface */
177 static int lm3s_ssiClose(struct KFile *fd)
179 LM3SSSI *fds = LM3SSSI_CAST(fd);
182 HWREG(fds->addr + SSI_O_CR1) &= ~SSI_CR1_SSE;
187 * Initialize a LM3S SSI driver.
189 void lm3s_ssiInit(struct LM3SSSI *fds, uint32_t addr, uint32_t frame, int mode,
190 int bitrate, uint32_t data_width)
192 memset(fds, 0, sizeof(*fds));
193 DB(fds->fd._type = KFT_LM3SSSI);
195 /* TODO: only 8-bit frame size is supported */
196 ASSERT(data_width == 8);
198 fds->fd.write = lm3s_ssiWrite;
199 fds->fd.read = lm3s_ssiRead;
200 fds->fd.close = lm3s_ssiClose;
201 fds->fd.flush = lm3s_ssiFlush;
204 lm3s_ssiOpen(addr, frame, mode, bitrate, data_width);