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git.ipfire.org Git - people/ms/u-boot.git/blob - drivers/spi/atmel_spi.c
2 * Copyright (C) 2007 Atmel Corporation
4 * See file CREDITS for list of people who contributed to this
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of
10 * the License, or (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
28 #include <asm/arch/clk.h>
29 #include <asm/arch/hardware.h>
31 #include "atmel_spi.h"
33 static int spi_has_wdrbt(struct atmel_spi_slave
*slave
)
37 ver
= spi_readl(slave
, VERSION
);
39 return (ATMEL_SPI_VERSION_REV(ver
) >= 0x210);
47 struct spi_slave
*spi_setup_slave(unsigned int bus
, unsigned int cs
,
48 unsigned int max_hz
, unsigned int mode
)
50 struct atmel_spi_slave
*as
;
55 if (!spi_cs_is_valid(bus
, cs
))
60 regs
= (void *)ATMEL_BASE_SPI0
;
62 #ifdef ATMEL_BASE_SPI1
64 regs
= (void *)ATMEL_BASE_SPI1
;
67 #ifdef ATMEL_BASE_SPI2
69 regs
= (void *)ATMEL_BASE_SPI2
;
72 #ifdef ATMEL_BASE_SPI3
74 regs
= (void *)ATMEL_BASE_SPI3
;
82 scbr
= (get_spi_clk_rate(bus
) + max_hz
- 1) / max_hz
;
83 if (scbr
> ATMEL_SPI_CSRx_SCBR_MAX
)
84 /* Too low max SCK rate */
89 csrx
= ATMEL_SPI_CSRx_SCBR(scbr
);
90 csrx
|= ATMEL_SPI_CSRx_BITS(ATMEL_SPI_BITS_8
);
91 if (!(mode
& SPI_CPHA
))
92 csrx
|= ATMEL_SPI_CSRx_NCPHA
;
94 csrx
|= ATMEL_SPI_CSRx_CPOL
;
96 as
= spi_alloc_slave(struct atmel_spi_slave
, bus
, cs
);
101 as
->mr
= ATMEL_SPI_MR_MSTR
| ATMEL_SPI_MR_MODFDIS
102 | ATMEL_SPI_MR_PCS(~(1 << cs
) & 0xf);
103 if (spi_has_wdrbt(as
))
104 as
->mr
|= ATMEL_SPI_MR_WDRBT
;
106 spi_writel(as
, CSR(cs
), csrx
);
111 void spi_free_slave(struct spi_slave
*slave
)
113 struct atmel_spi_slave
*as
= to_atmel_spi(slave
);
118 int spi_claim_bus(struct spi_slave
*slave
)
120 struct atmel_spi_slave
*as
= to_atmel_spi(slave
);
122 /* Enable the SPI hardware */
123 spi_writel(as
, CR
, ATMEL_SPI_CR_SPIEN
);
126 * Select the slave. This should set SCK to the correct
127 * initial state, etc.
129 spi_writel(as
, MR
, as
->mr
);
134 void spi_release_bus(struct spi_slave
*slave
)
136 struct atmel_spi_slave
*as
= to_atmel_spi(slave
);
138 /* Disable the SPI hardware */
139 spi_writel(as
, CR
, ATMEL_SPI_CR_SPIDIS
);
142 int spi_xfer(struct spi_slave
*slave
, unsigned int bitlen
,
143 const void *dout
, void *din
, unsigned long flags
)
145 struct atmel_spi_slave
*as
= to_atmel_spi(slave
);
150 const u8
*txp
= dout
;
155 /* Finish any previously submitted transfers */
159 * TODO: The controller can do non-multiple-of-8 bit
160 * transfers, but this driver currently doesn't support it.
162 * It's also not clear how such transfers are supposed to be
163 * represented as a stream of bytes...this is a limitation of
164 * the current SPI interface.
167 /* Errors always terminate an ongoing transfer */
168 flags
|= SPI_XFER_END
;
175 * The controller can do automatic CS control, but it is
176 * somewhat quirky, and it doesn't really buy us much anyway
177 * in the context of U-Boot.
179 if (flags
& SPI_XFER_BEGIN
) {
180 spi_cs_activate(slave
);
182 * sometimes the RDR is not empty when we get here,
183 * in theory that should not happen, but it DOES happen.
184 * Read it here to be on the safe side.
185 * That also clears the OVRES flag. Required if the
186 * following loop exits due to OVRES!
191 for (len_tx
= 0, len_rx
= 0; len_rx
< len
; ) {
192 status
= spi_readl(as
, SR
);
194 if (status
& ATMEL_SPI_SR_OVRES
)
197 if (len_tx
< len
&& (status
& ATMEL_SPI_SR_TDRE
)) {
202 spi_writel(as
, TDR
, value
);
205 if (status
& ATMEL_SPI_SR_RDRF
) {
206 value
= spi_readl(as
, RDR
);
214 if (flags
& SPI_XFER_END
) {
216 * Wait until the transfer is completely done before
220 status
= spi_readl(as
, SR
);
221 } while (!(status
& ATMEL_SPI_SR_TXEMPTY
));
223 spi_cs_deactivate(slave
);