spi/altera_spi: Add cs_change support
The Linux kernel says (spi.h) : * All SPI transfers start with the relevant chipselect active. Normally * it stays selected until after the last transfer in a message. Drivers * can affect the chipselect signal using cs_change. * * (i) If the transfer isn't the last one in the message, this flag is * used to make the chipselect briefly go inactive in the middle of the * message. Toggling chipselect in this way may be needed to terminate * a chip command, letting a single spi_message perform all of group of * chip transactions together. * * (ii) When the transfer is the last one in the message, the chip may * stay selected until the next transfer. On multi-device SPI busses * with nothing blocking messages going to other devices, this is just * a performance hint; starting a message to another device deselects * this one. But in other cases, this can be used to ensure correctness. * Some devices need protocol transactions to be built from a series of * spi_message submissions, where the content of one message is * determined by the results of previous messages and where the whole * transaction * ends when the chipselect goes intactive. In other words, cs_change changes the default chipselect *behavior*. Support of cs_change is necessary to implement the mci spi driver. This patch also fix few things: Passing the bus number to the brand new master device. Disable chipselect during master->setup. Signed-off-by: Franck Jullien <franck.jullien@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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@ -8,6 +8,7 @@ struct spi_altera_master {
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int spi_mode;
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int databits;
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int speed;
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int bus_num;
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};
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struct altera_spi {
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@ -25,6 +25,9 @@
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#include <io.h>
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#include <asm/spi.h>
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#include <asm/nios2-io.h>
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#include <clock.h>
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static void altera_spi_cs_inactive(struct spi_device *spi);
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static int altera_spi_setup(struct spi_device *spi)
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{
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@ -49,6 +52,8 @@ static int altera_spi_setup(struct spi_device *spi)
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return -1;
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}
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altera_spi_cs_inactive(spi);
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dev_dbg(master->dev, " mode 0x%08x, bits_per_word: %d, speed: %d\n",
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spi->mode, spi->bits_per_word, altera_spi->speed);
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@ -167,19 +172,38 @@ static int altera_spi_transfer(struct spi_device *spi, struct spi_message *mesg)
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struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
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struct nios_spi *nios_spi = altera_spi->regs;
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struct spi_transfer *t;
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unsigned int cs_change;
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const int nsecs = 50;
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altera_spi_cs_active(spi);
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cs_change = 0;
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mesg->actual_length = 0;
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list_for_each_entry(t, &mesg->transfers, transfer_list) {
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if (cs_change) {
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ndelay(nsecs);
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altera_spi_cs_inactive(spi);
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ndelay(nsecs);
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altera_spi_cs_active(spi);
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}
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cs_change = t->cs_change;
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mesg->actual_length += altera_spi_do_xfer(spi, t);
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if (cs_change) {
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altera_spi_cs_active(spi);
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}
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}
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/* Wait the end of any pending transfer */
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while ((readl(&nios_spi->status) & NIOS_SPI_TMT) == 0);
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altera_spi_cs_inactive(spi);
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if (!cs_change)
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altera_spi_cs_inactive(spi);
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return 0;
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}
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@ -199,6 +223,7 @@ static int altera_spi_probe(struct device_d *dev)
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master->setup = altera_spi_setup;
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master->transfer = altera_spi_transfer;
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master->num_chipselect = pdata->num_chipselect;
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master->bus_num = pdata->bus_num;
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altera_spi->regs = dev_request_mem_region(dev, 0);
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altera_spi->databits = pdata->databits;
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