spi: microchip-core-qspi: Support per spi-mem operation frequency switches

Every ->exec_op() call correctly configures the spi bus speed to the
maximum allowed frequency for the memory using the constant spi default
parameter. Since we can now have per-operation constraints, let's use
the value that comes from the spi-mem operation structure instead. In
case there is no specific limitation for this operation, the default spi
device value will be given anyway.

This controller however performed a frequency check, which is also
observed during the ->check_op() phase.

The per-operation frequency capability is thus advertised to the spi-mem
core.

Cc: Conor Dooley <conor.dooley@microchip.com>
Cc: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://patch.msgid.link/20241224-winbond-6-11-rc1-quad-support-v2-9-ad218dbc406f@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: miquelraynal

drivers/spi/spi-microchip-core-qspi.c

@@ -265,7 +265,8 @@ static irqreturn_t mchp_coreqspi_isr(int irq, void *dev_id)
 	return ret;
 }
 
-static int mchp_coreqspi_setup_clock(struct mchp_coreqspi *qspi, struct spi_device *spi)
+static int mchp_coreqspi_setup_clock(struct mchp_coreqspi *qspi, struct spi_device *spi,
+				     const struct spi_mem_op *op)
 {
 	unsigned long clk_hz;
 	u32 control, baud_rate_val = 0;
@@ -274,11 +275,11 @@ static int mchp_coreqspi_setup_clock(struct mchp_coreqspi *qspi, struct spi_devi
 	if (!clk_hz)
 		return -EINVAL;
 
-	baud_rate_val = DIV_ROUND_UP(clk_hz, 2 * spi->max_speed_hz);
+	baud_rate_val = DIV_ROUND_UP(clk_hz, 2 * op->max_freq);
 	if (baud_rate_val > MAX_DIVIDER || baud_rate_val < MIN_DIVIDER) {
 		dev_err(&spi->dev,
 			"could not configure the clock for spi clock %d Hz & system clock %ld Hz\n",
-			spi->max_speed_hz, clk_hz);
+			op->max_freq, clk_hz);
 		return -EINVAL;
 	}
 
@@ -399,7 +400,7 @@ static int mchp_coreqspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *o
 	if (err)
 		goto error;
 
-	err = mchp_coreqspi_setup_clock(qspi, mem->spi);
+	err = mchp_coreqspi_setup_clock(qspi, mem->spi, op);
 	if (err)
 		goto error;
 
@@ -457,6 +458,10 @@ static int mchp_coreqspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *o
 
 static bool mchp_coreqspi_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
 {
+	struct mchp_coreqspi *qspi = spi_controller_get_devdata(mem->spi->controller);
+	unsigned long clk_hz;
+	u32 baud_rate_val;
+
 	if (!spi_mem_default_supports_op(mem, op))
 		return false;
 
@@ -479,6 +484,14 @@ static bool mchp_coreqspi_supports_op(struct spi_mem *mem, const struct spi_mem_
 			return false;
 	}
 
+	clk_hz = clk_get_rate(qspi->clk);
+	if (!clk_hz)
+		return false;
+
+	baud_rate_val = DIV_ROUND_UP(clk_hz, 2 * op->max_freq);
+	if (baud_rate_val > MAX_DIVIDER || baud_rate_val < MIN_DIVIDER)
+		return false;
+
 	return true;
 }
 
@@ -498,6 +511,10 @@ static const struct spi_controller_mem_ops mchp_coreqspi_mem_ops = {
 	.exec_op = mchp_coreqspi_exec_op,
 };
 
+static const struct spi_controller_mem_caps mchp_coreqspi_mem_caps = {
+	.per_op_freq = true,
+};
+
 static int mchp_coreqspi_probe(struct platform_device *pdev)
 {
 	struct spi_controller *ctlr;
@@ -540,6 +557,7 @@ static int mchp_coreqspi_probe(struct platform_device *pdev)
 
 	ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
 	ctlr->mem_ops = &mchp_coreqspi_mem_ops;
+	ctlr->mem_caps = &mchp_coreqspi_mem_caps;
 	ctlr->setup = mchp_coreqspi_setup_op;
 	ctlr->mode_bits = SPI_CPOL | SPI_CPHA | SPI_RX_DUAL | SPI_RX_QUAD |
 			  SPI_TX_DUAL | SPI_TX_QUAD;