spi: qup: Enable chip select support

Enable chip select support for QUP versions later than v1. The
chip select support was broken in QUP version 1. Hence the chip
select support was removed earlier in an earlier commit
(4a8573abe "spi: qup: Remove chip select function"). Since the
chip select support is functional in recent versions of QUP,
re-enabling it for QUP versions later than v1.

Signed-off-by: Sham Muthayyan <smuthayy@codeaurora.org>
Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-qup.c

@@ -750,6 +750,24 @@ err_tx:
 	return ret;
 }
 
+static void spi_qup_set_cs(struct spi_device *spi, bool val)
+{
+	struct spi_qup *controller;
+	u32 spi_ioc;
+	u32 spi_ioc_orig;
+
+	controller = spi_master_get_devdata(spi->master);
+	spi_ioc = readl_relaxed(controller->base + SPI_IO_CONTROL);
+	spi_ioc_orig = spi_ioc;
+	if (!val)
+		spi_ioc |= SPI_IO_C_FORCE_CS;
+	else
+		spi_ioc &= ~SPI_IO_C_FORCE_CS;
+
+	if (spi_ioc != spi_ioc_orig)
+		writel_relaxed(spi_ioc, controller->base + SPI_IO_CONTROL);
+}
+
 static int spi_qup_probe(struct platform_device *pdev)
 {
 	struct spi_master *master;
@@ -846,6 +864,9 @@ static int spi_qup_probe(struct platform_device *pdev)
 	if (of_device_is_compatible(dev->of_node, "qcom,spi-qup-v1.1.1"))
 		controller->qup_v1 = 1;
 
+	if (!controller->qup_v1)
+		master->set_cs = spi_qup_set_cs;
+
 	spin_lock_init(&controller->lock);
 	init_completion(&controller->done);