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![Guennadi Liakhovetski](/assets/img/avatar_default.png)
Some SPI devices have special requirements on chip-select handling. With this patch we can use a GPIO as a chip-select and strictly follow the SPI_XFER_BEGIN and SPI_XFER_END flags. Signed-off-by: Guennadi Liakhovetski <lg@denx.de> Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
250 lines
6.1 KiB
C
250 lines
6.1 KiB
C
/*
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* Copyright (C) 2008, Guennadi Liakhovetski <lg@denx.de>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*
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*/
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#include <common.h>
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#include <malloc.h>
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#include <spi.h>
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#include <asm/errno.h>
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#include <asm/io.h>
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#ifdef CONFIG_MX27
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/* i.MX27 has a completely wrong register layout and register definitions in the
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* datasheet, the correct one is in the Freescale's Linux driver */
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#error "i.MX27 CSPI not supported due to drastic differences in register definisions" \
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"See linux mxc_spi driver from Freescale for details."
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#else
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#include <asm/arch/mx31.h>
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#define MXC_CSPIRXDATA 0x00
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#define MXC_CSPITXDATA 0x04
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#define MXC_CSPICTRL 0x08
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#define MXC_CSPIINT 0x0C
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#define MXC_CSPIDMA 0x10
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#define MXC_CSPISTAT 0x14
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#define MXC_CSPIPERIOD 0x18
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#define MXC_CSPITEST 0x1C
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#define MXC_CSPIRESET 0x00
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#define MXC_CSPICTRL_EN (1 << 0)
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#define MXC_CSPICTRL_MODE (1 << 1)
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#define MXC_CSPICTRL_XCH (1 << 2)
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#define MXC_CSPICTRL_SMC (1 << 3)
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#define MXC_CSPICTRL_POL (1 << 4)
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#define MXC_CSPICTRL_PHA (1 << 5)
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#define MXC_CSPICTRL_SSCTL (1 << 6)
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#define MXC_CSPICTRL_SSPOL (1 << 7)
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#define MXC_CSPICTRL_CHIPSELECT(x) (((x) & 0x3) << 24)
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#define MXC_CSPICTRL_BITCOUNT(x) (((x) & 0x1f) << 8)
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#define MXC_CSPICTRL_DATARATE(x) (((x) & 0x7) << 16)
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#define MXC_CSPIPERIOD_32KHZ (1 << 15)
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static unsigned long spi_bases[] = {
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0x43fa4000,
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0x50010000,
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0x53f84000,
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};
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#endif
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struct mxc_spi_slave {
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struct spi_slave slave;
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unsigned long base;
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u32 ctrl_reg;
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int gpio;
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};
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static inline struct mxc_spi_slave *to_mxc_spi_slave(struct spi_slave *slave)
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{
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return container_of(slave, struct mxc_spi_slave, slave);
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}
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static inline u32 reg_read(unsigned long addr)
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{
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return *(volatile unsigned long*)addr;
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}
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static inline void reg_write(unsigned long addr, u32 val)
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{
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*(volatile unsigned long*)addr = val;
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}
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static u32 spi_xchg_single(struct spi_slave *slave, u32 data, int bitlen,
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unsigned long flags)
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{
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struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
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unsigned int cfg_reg = reg_read(mxcs->base + MXC_CSPICTRL);
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mxcs->ctrl_reg = (mxcs->ctrl_reg & ~MXC_CSPICTRL_BITCOUNT(31)) |
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MXC_CSPICTRL_BITCOUNT(bitlen - 1);
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if (cfg_reg != mxcs->ctrl_reg)
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reg_write(mxcs->base + MXC_CSPICTRL, mxcs->ctrl_reg);
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if (mxcs->gpio > 0 && (flags & SPI_XFER_BEGIN))
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mx31_gpio_set(mxcs->gpio, mxcs->ctrl_reg & MXC_CSPICTRL_SSPOL);
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reg_write(mxcs->base + MXC_CSPITXDATA, data);
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reg_write(mxcs->base + MXC_CSPICTRL, mxcs->ctrl_reg | MXC_CSPICTRL_XCH);
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while (reg_read(mxcs->base + MXC_CSPICTRL) & MXC_CSPICTRL_XCH)
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;
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if (mxcs->gpio > 0 && (flags & SPI_XFER_END)) {
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mx31_gpio_set(mxcs->gpio,
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!(mxcs->ctrl_reg & MXC_CSPICTRL_SSPOL));
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}
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return reg_read(mxcs->base + MXC_CSPIRXDATA);
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}
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int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
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void *din, unsigned long flags)
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{
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int n_blks = (bitlen + 31) / 32;
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u32 *out_l, *in_l;
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int i;
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if ((int)dout & 3 || (int)din & 3) {
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printf("Error: unaligned buffers in: %p, out: %p\n", din, dout);
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return 1;
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}
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for (i = 0, in_l = (u32 *)din, out_l = (u32 *)dout;
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i < n_blks;
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i++, in_l++, out_l++, bitlen -= 32) {
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u32 data = spi_xchg_single(slave, *out_l, bitlen, flags);
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/* Check if we're only transfering 8 or 16 bits */
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if (!i) {
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if (bitlen < 9)
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*(u8 *)din = data;
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else if (bitlen < 17)
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*(u16 *)din = data;
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}
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}
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return 0;
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}
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void spi_init(void)
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{
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}
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static int decode_cs(struct mxc_spi_slave *mxcs, unsigned int cs)
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{
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int ret;
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/*
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* Some SPI devices require active chip-select over multiple
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* transactions, we achieve this using a GPIO. Still, the SPI
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* controller has to be configured to use one of its own chipselects.
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* To use this feature you have to call spi_setup_slave() with
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* cs = internal_cs | (gpio << 8), and you have to use some unused
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* on this SPI controller cs between 0 and 3.
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*/
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if (cs > 3) {
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mxcs->gpio = cs >> 8;
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cs &= 3;
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ret = mx31_gpio_direction(mxcs->gpio, MX31_GPIO_DIRECTION_OUT);
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if (ret) {
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printf("mxc_spi: cannot setup gpio %d\n", mxcs->gpio);
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return -EINVAL;
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}
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} else {
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mxcs->gpio = -1;
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}
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return cs;
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}
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struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
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unsigned int max_hz, unsigned int mode)
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{
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unsigned int ctrl_reg;
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struct mxc_spi_slave *mxcs;
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int ret;
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if (bus >= ARRAY_SIZE(spi_bases))
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return NULL;
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mxcs = malloc(sizeof(struct mxc_spi_slave));
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if (!mxcs)
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return NULL;
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ret = decode_cs(mxcs, cs);
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if (ret < 0) {
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free(mxcs);
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return NULL;
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}
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cs = ret;
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ctrl_reg = MXC_CSPICTRL_CHIPSELECT(cs) |
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MXC_CSPICTRL_BITCOUNT(31) |
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MXC_CSPICTRL_DATARATE(7) | /* FIXME: calculate data rate */
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MXC_CSPICTRL_EN |
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MXC_CSPICTRL_MODE;
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if (mode & SPI_CPHA)
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ctrl_reg |= MXC_CSPICTRL_PHA;
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if (!(mode & SPI_CPOL))
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ctrl_reg |= MXC_CSPICTRL_POL;
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if (mode & SPI_CS_HIGH)
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ctrl_reg |= MXC_CSPICTRL_SSPOL;
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mxcs->slave.bus = bus;
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mxcs->slave.cs = cs;
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mxcs->base = spi_bases[bus];
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mxcs->ctrl_reg = ctrl_reg;
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return &mxcs->slave;
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}
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void spi_free_slave(struct spi_slave *slave)
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{
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struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
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free(mxcs);
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}
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int spi_claim_bus(struct spi_slave *slave)
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{
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struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
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reg_write(mxcs->base + MXC_CSPIRESET, 1);
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udelay(1);
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reg_write(mxcs->base + MXC_CSPICTRL, mxcs->ctrl_reg);
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reg_write(mxcs->base + MXC_CSPIPERIOD,
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MXC_CSPIPERIOD_32KHZ);
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reg_write(mxcs->base + MXC_CSPIINT, 0);
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return 0;
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}
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void spi_release_bus(struct spi_slave *slave)
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{
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/* TODO: Shut the controller down */
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}
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