spi: meson-spicc: adapt burst handling for G12A support

The G12A SPICC controller variant has a different FIFO size and doesn't
handle the RX Half interrupt the same way as GXL & AXG variants.

Thus simplify the burst management and take in account a variable FIFO
size.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20200312133131.26430-8-narmstrong@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-meson-spicc.c

@@ -141,12 +141,10 @@
 #define writel_bits_relaxed(mask, val, addr) \
 	writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)
 
-#define SPICC_BURST_MAX	16
-#define SPICC_FIFO_HALF 10
-
 struct meson_spicc_data {
 	unsigned int			max_speed_hz;
 	unsigned int			min_speed_hz;
+	unsigned int			fifo_size;
 	bool				has_oen;
 	bool				has_enhance_clk_div;
 };
@@ -166,8 +164,6 @@ struct meson_spicc_device {
 	unsigned long			tx_remain;
 	unsigned long			rx_remain;
 	unsigned long			xfer_remain;
-	bool				is_burst_end;
-	bool				is_last_burst;
 };
 
 static void meson_spicc_oen_enable(struct meson_spicc_device *spicc)
@@ -191,7 +187,7 @@ static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc)
 
 static inline bool meson_spicc_rxready(struct meson_spicc_device *spicc)
 {
-	return FIELD_GET(SPICC_RH | SPICC_RR | SPICC_RF_EN,
+	return FIELD_GET(SPICC_RH | SPICC_RR | SPICC_RF,
 			 readl_relaxed(spicc->base + SPICC_STATREG));
 }
 
@@ -246,34 +242,22 @@ static inline void meson_spicc_tx(struct meson_spicc_device *spicc)
 			       spicc->base + SPICC_TXDATA);
 }
 
-static inline u32 meson_spicc_setup_rx_irq(struct meson_spicc_device *spicc,
-					   u32 irq_ctrl)
+static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc)
 {
-	if (spicc->rx_remain > SPICC_FIFO_HALF)
-		irq_ctrl |= SPICC_RH_EN;
-	else
-		irq_ctrl |= SPICC_RR_EN;
-
-	return irq_ctrl;
-}
 
-static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc,
-					   unsigned int burst_len)
-{
+	unsigned int burst_len = min_t(unsigned int,
+				       spicc->xfer_remain /
+				       spicc->bytes_per_word,
+				       spicc->data->fifo_size);
 	/* Setup Xfer variables */
 	spicc->tx_remain = burst_len;
 	spicc->rx_remain = burst_len;
 	spicc->xfer_remain -= burst_len * spicc->bytes_per_word;
-	spicc->is_burst_end = false;
-	if (burst_len < SPICC_BURST_MAX || !spicc->xfer_remain)
-		spicc->is_last_burst = true;
-	else
-		spicc->is_last_burst = false;
 
 	/* Setup burst length */
 	writel_bits_relaxed(SPICC_BURSTLENGTH_MASK,
 			FIELD_PREP(SPICC_BURSTLENGTH_MASK,
-				burst_len),
+				burst_len - 1),
 			spicc->base + SPICC_CONREG);
 
 	/* Fill TX FIFO */
@@ -283,61 +267,26 @@ static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc,
 static irqreturn_t meson_spicc_irq(int irq, void *data)
 {
 	struct meson_spicc_device *spicc = (void *) data;
-	u32 ctrl = readl_relaxed(spicc->base + SPICC_INTREG);
-	u32 stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
 
-	ctrl &= ~(SPICC_RH_EN | SPICC_RR_EN);
+	writel_bits_relaxed(SPICC_TC, SPICC_TC, spicc->base + SPICC_STATREG);
 
 	/* Empty RX FIFO */
 	meson_spicc_rx(spicc);
 
-	/* Enable TC interrupt since we transferred everything */
-	if (!spicc->tx_remain && !spicc->rx_remain) {
-		spicc->is_burst_end = true;
-
-		/* Enable TC interrupt */
-		ctrl |= SPICC_TC_EN;
-
-		/* Reload IRQ status */
-		stat = readl_relaxed(spicc->base + SPICC_STATREG) & ctrl;
-	}
-
-	/* Check transfer complete */
-	if ((stat & SPICC_TC) && spicc->is_burst_end) {
-		unsigned int burst_len;
-
-		/* Clear TC bit */
-		writel_relaxed(SPICC_TC, spicc->base + SPICC_STATREG);
-
-		/* Disable TC interrupt */
-		ctrl &= ~SPICC_TC_EN;
-
-		if (spicc->is_last_burst) {
-			/* Disable all IRQs */
-			writel(0, spicc->base + SPICC_INTREG);
-
-			spi_finalize_current_transfer(spicc->master);
+	if (!spicc->xfer_remain) {
+		/* Disable all IRQs */
+		writel(0, spicc->base + SPICC_INTREG);
 
-			return IRQ_HANDLED;
-		}
+		spi_finalize_current_transfer(spicc->master);
 
-		burst_len = min_t(unsigned int,
-				  spicc->xfer_remain / spicc->bytes_per_word,
-				  SPICC_BURST_MAX);
-
-		/* Setup burst */
-		meson_spicc_setup_burst(spicc, burst_len);
-
-		/* Restart burst */
-		writel_bits_relaxed(SPICC_XCH, SPICC_XCH,
-				    spicc->base + SPICC_CONREG);
+		return IRQ_HANDLED;
 	}
 
-	/* Setup RX interrupt trigger */
-	ctrl = meson_spicc_setup_rx_irq(spicc, ctrl);
+	/* Setup burst */
+	meson_spicc_setup_burst(spicc);
 
-	/* Reconfigure interrupts */
-	writel(ctrl, spicc->base + SPICC_INTREG);
+	/* Start burst */
+	writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG);
 
 	return IRQ_HANDLED;
 }
@@ -405,6 +354,28 @@ static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
 	clk_set_rate(spicc->clk, xfer->speed_hz);
 
 	meson_spicc_auto_io_delay(spicc);
+
+	writel_relaxed(0, spicc->base + SPICC_DMAREG);
+}
+
+static void meson_spicc_reset_fifo(struct meson_spicc_device *spicc)
+{
+	u32 data;
+
+	if (spicc->data->has_oen)
+		writel_bits_relaxed(SPICC_ENH_MAIN_CLK_AO,
+				    SPICC_ENH_MAIN_CLK_AO,
+				    spicc->base + SPICC_ENH_CTL0);
+
+	writel_bits_relaxed(SPICC_FIFORST_W1_MASK, SPICC_FIFORST_W1_MASK,
+			    spicc->base + SPICC_TESTREG);
+
+	while (meson_spicc_rxready(spicc))
+		data = readl_relaxed(spicc->base + SPICC_RXDATA);
+
+	if (spicc->data->has_oen)
+		writel_bits_relaxed(SPICC_ENH_MAIN_CLK_AO, 0,
+				    spicc->base + SPICC_ENH_CTL0);
 }
 
 static int meson_spicc_transfer_one(struct spi_master *master,
@@ -412,8 +383,6 @@ static int meson_spicc_transfer_one(struct spi_master *master,
 				    struct spi_transfer *xfer)
 {
 	struct meson_spicc_device *spicc = spi_master_get_devdata(master);
-	unsigned int burst_len;
-	u32 irq = 0;
 
 	/* Store current transfer */
 	spicc->xfer = xfer;
@@ -427,22 +396,22 @@ static int meson_spicc_transfer_one(struct spi_master *master,
 	spicc->bytes_per_word =
 	   DIV_ROUND_UP(spicc->xfer->bits_per_word, 8);
 
+	if (xfer->len % spicc->bytes_per_word)
+		return -EINVAL;
+
 	/* Setup transfer parameters */
 	meson_spicc_setup_xfer(spicc, xfer);
 
-	burst_len = min_t(unsigned int,
-			  spicc->xfer_remain / spicc->bytes_per_word,
-			  SPICC_BURST_MAX);
-
-	meson_spicc_setup_burst(spicc, burst_len);
+	meson_spicc_reset_fifo(spicc);
 
-	irq = meson_spicc_setup_rx_irq(spicc, irq);
+	/* Setup burst */
+	meson_spicc_setup_burst(spicc);
 
 	/* Start burst */
 	writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG);
 
 	/* Enable interrupts */
-	writel_relaxed(irq, spicc->base + SPICC_INTREG);
+	writel_relaxed(SPICC_TC_EN, spicc->base + SPICC_INTREG);
 
 	return 1;
 }
@@ -499,7 +468,7 @@ static int meson_spicc_prepare_message(struct spi_master *master,
 	/* Setup no wait cycles by default */
 	writel_relaxed(0, spicc->base + SPICC_PERIODREG);
 
-	writel_bits_relaxed(BIT(24), BIT(24), spicc->base + SPICC_TESTREG);
+	writel_bits_relaxed(SPICC_LBC_W1, 0, spicc->base + SPICC_TESTREG);
 
 	return 0;
 }
@@ -797,11 +766,13 @@ static int meson_spicc_remove(struct platform_device *pdev)
 static const struct meson_spicc_data meson_spicc_gx_data = {
 	.max_speed_hz		= 30000000,
 	.min_speed_hz		= 325000,
+	.fifo_size		= 16,
 };
 
 static const struct meson_spicc_data meson_spicc_axg_data = {
 	.max_speed_hz		= 80000000,
 	.min_speed_hz		= 325000,
+	.fifo_size		= 16,
 	.has_oen		= true,
 	.has_enhance_clk_div	= true,
 };