[PATCH 1/6] spi: stm32: Add SPI_READY mode to spi controller

["Clément Le Goffic" <clement.legoffic@foss.st.com>]

The spi ready functionality is supported by our peripheral in host and
target modes on STM32MP2x SoCs.
Update our spi controller driver to allow devices to use this
functionality.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
---
 drivers/spi/spi-stm32.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index da3517d7102d..2bcd4a43676d 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -154,6 +154,9 @@
 /* STM32H7_SPI_I2SCFGR bit fields */
 #define STM32H7_SPI_I2SCFGR_I2SMOD	BIT(0)
 
+/* STM32MP25_SPICFG2 bit fields */
+#define STM32MP25_SPI_CFG2_RDIOM	BIT(13)
+
 /* STM32MP25 SPI registers bit fields */
 #define STM32MP25_SPI_HWCFGR1			0x3F0
 
@@ -222,6 +225,7 @@ struct stm32_spi_reg {
  * @rx: SPI RX data register
  * @tx: SPI TX data register
  * @fullcfg: SPI full or limited feature set register
+ * @rdy_en: SPI ready feature register
  */
 struct stm32_spi_regspec {
 	const struct stm32_spi_reg en;
@@ -235,6 +239,7 @@ struct stm32_spi_regspec {
 	const struct stm32_spi_reg rx;
 	const struct stm32_spi_reg tx;
 	const struct stm32_spi_reg fullcfg;
+	const struct stm32_spi_reg rdy_en;
 };
 
 struct stm32_spi;
@@ -415,6 +420,8 @@ static const struct stm32_spi_regspec stm32mp25_spi_regspec = {
 	.tx = { STM32H7_SPI_TXDR },
 
 	.fullcfg = { STM32MP25_SPI_HWCFGR1, STM32MP25_SPI_HWCFGR1_FULLCFG },
+
+	.rdy_en = { STM32H7_SPI_CFG2, STM32MP25_SPI_CFG2_RDIOM },
 };
 
 static inline void stm32_spi_set_bits(struct stm32_spi *spi,
@@ -1172,15 +1179,21 @@ static int stm32_spi_prepare_msg(struct spi_controller *ctrl,
 	else
 		clrb |= spi->cfg->regs->cs_high.mask;
 
-	dev_dbg(spi->dev, "cpol=%d cpha=%d lsb_first=%d cs_high=%d\n",
+	if (spi_dev->mode & SPI_READY)
+		setb |= spi->cfg->regs->rdy_en.mask;
+	else
+		clrb |= spi->cfg->regs->rdy_en.mask;
+
+	dev_dbg(spi->dev, "cpol=%d cpha=%d lsb_first=%d cs_high=%d rdy=%d\n",
 		!!(spi_dev->mode & SPI_CPOL),
 		!!(spi_dev->mode & SPI_CPHA),
 		!!(spi_dev->mode & SPI_LSB_FIRST),
-		!!(spi_dev->mode & SPI_CS_HIGH));
+		!!(spi_dev->mode & SPI_CS_HIGH),
+		!!(spi_dev->mode & SPI_READY));
 
 	spin_lock_irqsave(&spi->lock, flags);
 
-	/* CPOL, CPHA and LSB FIRST bits have common register */
+	/* CPOL, CPHA, LSB FIRST, CS_HIGH and RDY_EN bits have common register */
 	if (clrb || setb)
 		writel_relaxed(
 			(readl_relaxed(spi->base + spi->cfg->regs->cpol.reg) &
@@ -1768,6 +1781,13 @@ static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
 	spi->cur_bpw = transfer->bits_per_word;
 	spi->cfg->set_bpw(spi);
 
+	if (spi_dev->mode & SPI_READY && spi->cur_bpw < 8) {
+		writel_relaxed(readl_relaxed(spi->base + spi->cfg->regs->rdy_en.reg) &
+				~spi->cfg->regs->rdy_en.mask,
+					spi->base + spi->cfg->regs->rdy_en.reg);
+		dev_dbg(spi->dev, "RDY logic disabled as bits per word < 8\n");
+	}
+
 	/* Update spi->cur_speed with real clock speed */
 	if (STM32_SPI_HOST_MODE(spi)) {
 		mbr = stm32_spi_prepare_mbr(spi, transfer->speed_hz,
@@ -2179,7 +2199,7 @@ static int stm32_spi_probe(struct platform_device *pdev)
 	ctrl->auto_runtime_pm = true;
 	ctrl->bus_num = pdev->id;
 	ctrl->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST |
-			  SPI_3WIRE;
+			  SPI_3WIRE | SPI_READY;
 	ctrl->bits_per_word_mask = spi->cfg->get_bpw_mask(spi);
 	ctrl->max_speed_hz = spi->clk_rate / spi->cfg->baud_rate_div_min;
 	ctrl->min_speed_hz = spi->clk_rate / spi->cfg->baud_rate_div_max;

-- 
2.43.0