spi: aspeed: Add support for direct mapping

Use direct mapping to read the flash device contents. This operation
mode is called "Command mode" on Aspeed SoC SMC controllers. It uses a
Control Register for the settings to apply when a memory operation is
performed on the flash device mapping window.

If the window is not big enough, fall back to the "User mode" to
perform the read.

Direct mapping for writes will come later when validated.
Reviewed-by: Joel Stanley <joel@jms.id.au>
Tested-by: Joel Stanley <joel@jms.id.au>
Tested-by: Tao Ren <rentao.bupt@gmail.com>
Tested-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Link: https://lore.kernel.org/r/20220509175616.1089346-5-clg@kaod.orgSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-aspeed-smc.c

@@ -411,10 +411,78 @@ static int aspeed_spi_chip_set_default_window(struct aspeed_spi_chip *chip)
 	return chip->ahb_window_size ? 0 : -1;
 }
 
+static int aspeed_spi_dirmap_create(struct spi_mem_dirmap_desc *desc)
+{
+	struct aspeed_spi *aspi = spi_controller_get_devdata(desc->mem->spi->master);
+	struct aspeed_spi_chip *chip = &aspi->chips[desc->mem->spi->chip_select];
+	struct spi_mem_op *op = &desc->info.op_tmpl;
+	u32 ctl_val;
+	int ret = 0;
+
+	chip->clk_freq = desc->mem->spi->max_speed_hz;
+
+	/* Only for reads */
+	if (op->data.dir != SPI_MEM_DATA_IN)
+		return -EOPNOTSUPP;
+
+	if (desc->info.length > chip->ahb_window_size)
+		dev_warn(aspi->dev, "CE%d window (%dMB) too small for mapping",
+			 chip->cs, chip->ahb_window_size >> 20);
+
+	/* Define the default IO read settings */
+	ctl_val = readl(chip->ctl) & ~CTRL_IO_CMD_MASK;
+	ctl_val |= aspeed_spi_get_io_mode(op) |
+		op->cmd.opcode << CTRL_COMMAND_SHIFT |
+		CTRL_IO_DUMMY_SET(op->dummy.nbytes / op->dummy.buswidth) |
+		CTRL_IO_MODE_READ;
+
+	/* Tune 4BYTE address mode */
+	if (op->addr.nbytes) {
+		u32 addr_mode = readl(aspi->regs + CE_CTRL_REG);
+
+		if (op->addr.nbytes == 4)
+			addr_mode |= (0x11 << chip->cs);
+		else
+			addr_mode &= ~(0x11 << chip->cs);
+		writel(addr_mode, aspi->regs + CE_CTRL_REG);
+	}
+
+	/* READ mode is the controller default setting */
+	chip->ctl_val[ASPEED_SPI_READ] = ctl_val;
+	writel(chip->ctl_val[ASPEED_SPI_READ], chip->ctl);
+
+	dev_info(aspi->dev, "CE%d read buswidth:%d [0x%08x]\n",
+		 chip->cs, op->data.buswidth, chip->ctl_val[ASPEED_SPI_READ]);
+
+	return ret;
+}
+
+static ssize_t aspeed_spi_dirmap_read(struct spi_mem_dirmap_desc *desc,
+				      u64 offset, size_t len, void *buf)
+{
+	struct aspeed_spi *aspi = spi_controller_get_devdata(desc->mem->spi->master);
+	struct aspeed_spi_chip *chip = &aspi->chips[desc->mem->spi->chip_select];
+
+	/* Switch to USER command mode if mapping window is too small */
+	if (chip->ahb_window_size < offset + len) {
+		int ret;
+
+		ret = aspeed_spi_read_user(chip, &desc->info.op_tmpl, offset, len, buf);
+		if (ret < 0)
+			return ret;
+	} else {
+		memcpy_fromio(buf, chip->ahb_base + offset, len);
+	}
+
+	return len;
+}
+
 static const struct spi_controller_mem_ops aspeed_spi_mem_ops = {
 	.supports_op = aspeed_spi_supports_op,
 	.exec_op = aspeed_spi_exec_op,
 	.get_name = aspeed_spi_get_name,
+	.dirmap_create = aspeed_spi_dirmap_create,
+	.dirmap_read = aspeed_spi_dirmap_read,
 };
 
 static void aspeed_spi_chip_set_type(struct aspeed_spi *aspi, unsigned int cs, int type)