spi: dw: 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.

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

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://patch.msgid.link/20241224-winbond-6-11-rc1-quad-support-v2-7-ad218dbc406f@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: miquelraynal

drivers/spi/spi-dw-core.c

@@ -677,7 +677,7 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	 * operation. Transmit-only mode is suitable for the rest of them.
 	 */
 	cfg.dfs = 8;
-	cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq);
+	cfg.freq = clamp(op->max_freq, 0U, dws->max_mem_freq);
 	if (op->data.dir == SPI_MEM_DATA_IN) {
 		cfg.tmode = DW_SPI_CTRLR0_TMOD_EPROMREAD;
 		cfg.ndf = op->data.nbytes;
@@ -894,6 +894,10 @@ static void dw_spi_hw_init(struct device *dev, struct dw_spi *dws)
 		dw_writel(dws, DW_SPI_CS_OVERRIDE, 0xF);
 }
 
+static const struct spi_controller_mem_caps dw_spi_mem_caps = {
+	.per_op_freq = true,
+};
+
 int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 {
 	struct spi_controller *host;
@@ -941,8 +945,10 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 		host->set_cs = dw_spi_set_cs;
 	host->transfer_one = dw_spi_transfer_one;
 	host->handle_err = dw_spi_handle_err;
-	if (dws->mem_ops.exec_op)
+	if (dws->mem_ops.exec_op) {
 		host->mem_ops = &dws->mem_ops;
+		host->mem_caps = &dw_spi_mem_caps;
+	}
 	host->max_speed_hz = dws->max_freq;
 	host->flags = SPI_CONTROLLER_GPIO_SS;
 	host->auto_runtime_pm = true;