[PATCH v6] spi: orion.c: Add direct access mode
Stefan Roese
sr at denx.de
Wed Apr 20 03:11:08 PDT 2016
This patch adds support for the direct write mode to the Orion SPI
driver which is used on the Marvell Armada based SoCs. In this direct
mode, all data written to (or read from) a specifically mapped MBus
window (linked to one SPI chip-select on one of the SPI controllers)
will be transferred directly to the SPI bus. Without the need to control
the SPI registers in between. This can improve the SPI transfer rate in
such cases.
Currently only the direct write mode is supported. This mode especially
benefits from the SPI direct mode, as the data bytes are written
head-to-head to the SPI bus, without any additional addresses, that
are also written in the direct read mode.
One use-case for this direct write mode is, programming a FPGA bitstream
image into the FPGA connected to the SPI bus at maximum speed.
This mode is described in chapter "22.5.2 Direct Write to SPI" in the
Marvell Armada XP Functional Spec Datasheet.
It should be possible to support SPI-NOR and SPI-NAND devices via
this direct access mode as well. But this needs further work, e.g.:
- The mapping of the MBus window needs to get extended to span
the complete flash device size
- The address / control data needs to get inserted into the SPI
controller registers
Signed-off-by: Stefan Roese <sr at denx.de>
Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement at free-electrons.com>
Cc: Andrew Lunn <andrew at lunn.ch>
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: Mark Brown <broonie at kernel.org>
---
v6:
- Switched from memcpy() to writesl() for the TX transfer.
- Only one page is mapped via ioremap as this is sufficient for
the currently implemented simple TX transfer.
- Removed max_transfer_size() as its not needed with the current
one page mapping that supports an unlimited amount of SPI data.
- Added a comment to the 'reg' description in the DT bindings
documentation as suggested by Arnd.
- Changed 'reg' and 'ranges' to use '<' and '>' in this file.
- Changed size to 0xffffffff in this file.
- Added a small paragraph to the commit text, describing the
possibility to support SPI-NOR & SPI-NAND devices via this
direct access mode.
v5:
- Added some documentation for the direct mode to the orion-spi DT
bindings document, including an example and a reference to the
mbus DT bindings documentation.
v4:
- Add max_transfer_size()
- Fall back from direct-write mode to PIO mode when
- transfer size is exceedeed
- non-8bit transfers
- Restrict to direct-write mode for now. SPI direct read mode can
be added later, when someone has a platform supporting this
mode.
v3:
- Used static MBus windows again, as suggested by Arnd
- No new DT bindings needed for this. The MBus windows need to be
configured in the 'reg' property of the SPI controller. This is
done in a separate patch for the Armada platforms.
- The direct mapping is configured and enable by adding the
specific MBus entry to the 'ranges' property of the 'soc' node
in the board dts file.
v2:
- Use one MBus window for each SPI controller instead of one for
for each SPI device. This MBus window is re-assigned, once the
CS changes.
- Assert the CS over the entire message
- Don't restrict the direct access mode to only direct write mode
- Add check for max size before using memcpy()
- Remove spidev from DT bindings documentation
.../devicetree/bindings/spi/spi-orion.txt | 49 +++++++++++++-
drivers/spi/spi-orion.c | 79 ++++++++++++++++++++++
2 files changed, 127 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/spi/spi-orion.txt b/Documentation/devicetree/bindings/spi/spi-orion.txt
index 98bc698..4f629cc 100644
--- a/Documentation/devicetree/bindings/spi/spi-orion.txt
+++ b/Documentation/devicetree/bindings/spi/spi-orion.txt
@@ -8,7 +8,15 @@ Required properties:
- "marvell,armada-380-spi", for the Armada 38x SoCs
- "marvell,armada-390-spi", for the Armada 39x SoCs
- "marvell,armada-xp-spi", for the Armada XP SoCs
-- reg : offset and length of the register set for the device
+- reg : offset and length of the register set for the device.
+ This property can optionally have additional entries to configure
+ the SPI direct access mode that some of the Marvell SoCs support
+ additionally to the normal indirect access (PIO) mode. The values
+ for the MBus "target" and "attribute" are defined in the Marvell
+ SoC "Functional Specifications" Manual in the chapter "Marvell
+ Core Processor Address Decoding".
+ The eight register sets following the control registers refer to
+ chip-select lines 0 through 7 respectively.
- cell-index : Which of multiple SPI controllers is this.
Optional properties:
- interrupts : Is currently not used.
@@ -23,3 +31,42 @@ Example:
interrupts = <23>;
status = "disabled";
};
+
+Example with SPI direct mode support (optionally):
+ spi0: spi at 10600 {
+ compatible = "marvell,orion-spi";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ cell-index = <0>;
+ reg = <MBUS_ID(0xf0, 0x01) 0x10600 0x28>, /* control */
+ <MBUS_ID(0x01, 0x1e) 0 0xffffffff>, /* CS0 */
+ <MBUS_ID(0x01, 0x5e) 0 0xffffffff>, /* CS1 */
+ <MBUS_ID(0x01, 0x9e) 0 0xffffffff>, /* CS2 */
+ <MBUS_ID(0x01, 0xde) 0 0xffffffff>, /* CS3 */
+ <MBUS_ID(0x01, 0x1f) 0 0xffffffff>, /* CS4 */
+ <MBUS_ID(0x01, 0x5f) 0 0xffffffff>, /* CS5 */
+ <MBUS_ID(0x01, 0x9f) 0 0xffffffff>, /* CS6 */
+ <MBUS_ID(0x01, 0xdf) 0 0xffffffff>; /* CS7 */
+ interrupts = <23>;
+ status = "disabled";
+ };
+
+To enable the direct mode, the board specific 'ranges' property in the
+'soc' node needs to add the entries for the desired SPI controllers
+and its chip-selects that are used in the direct mode instead of PIO
+mode. Here an example for this (SPI controller 0, device 1 and SPI
+controller 1, device 2 are used in direct mode. All other SPI device
+are used in the default indirect (PIO) mode):
+ soc {
+ /*
+ * Enable the SPI direct access by configuring an entry
+ * here in the board-specific ranges property
+ */
+ ranges = <MBUS_ID(0xf0, 0x01) 0 0 0xf1000000 0x100000>, /* internal regs */
+ <MBUS_ID(0x01, 0x1d) 0 0 0xfff00000 0x100000>, /* BootROM */
+ <MBUS_ID(0x01, 0x5e) 0 0 0xf1100000 0x10000>, /* SPI0-DEV1 */
+ <MBUS_ID(0x01, 0x9a) 0 0 0xf1110000 0x10000>; /* SPI1-DEV2 */
+
+For further information on the MBus bindings, please see the MBus
+DT documentation:
+Documentation/devicetree/bindings/bus/mvebu-mbus.txt
diff --git a/drivers/spi/spi-orion.c b/drivers/spi/spi-orion.c
index a87cfd4..3e20afd 100644
--- a/drivers/spi/spi-orion.c
+++ b/drivers/spi/spi-orion.c
@@ -18,6 +18,7 @@
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/clk.h>
#include <linux/sizes.h>
@@ -43,6 +44,9 @@
#define ORION_SPI_INT_CAUSE_REG 0x10
#define ORION_SPI_TIMING_PARAMS_REG 0x18
+/* Register for the "Direct Mode" */
+#define SPI_DIRECT_WRITE_CONFIG_REG 0x20
+
#define ORION_SPI_TMISO_SAMPLE_MASK (0x3 << 6)
#define ORION_SPI_TMISO_SAMPLE_1 (1 << 6)
#define ORION_SPI_TMISO_SAMPLE_2 (2 << 6)
@@ -78,11 +82,18 @@ struct orion_spi_dev {
bool is_errata_50mhz_ac;
};
+struct orion_direct_acc {
+ void __iomem *vaddr;
+ u32 size;
+};
+
struct orion_spi {
struct spi_master *master;
void __iomem *base;
struct clk *clk;
const struct orion_spi_dev *devdata;
+
+ struct orion_direct_acc direct_access[ORION_NUM_CHIPSELECTS];
};
static inline void __iomem *spi_reg(struct orion_spi *orion_spi, u32 reg)
@@ -372,10 +383,30 @@ orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
{
unsigned int count;
int word_len;
+ struct orion_spi *orion_spi;
+ int cs = spi->chip_select;
word_len = spi->bits_per_word;
count = xfer->len;
+ orion_spi = spi_master_get_devdata(spi->master);
+
+ /*
+ * Use SPI direct write mode if base address is available. Otherwise
+ * fall back to PIO mode for this transfer.
+ */
+ if ((orion_spi->direct_access[cs].vaddr) && (xfer->tx_buf) &&
+ (word_len == 8)) {
+ /*
+ * Send the TX-data to the SPI device via the direct
+ * mapped address window
+ */
+ writesl(orion_spi->direct_access[cs].vaddr, xfer->tx_buf,
+ DIV_ROUND_UP(count, 4));
+
+ return count;
+ }
+
if (word_len == 8) {
const u8 *tx = xfer->tx_buf;
u8 *rx = xfer->rx_buf;
@@ -425,6 +456,10 @@ static int orion_spi_reset(struct orion_spi *orion_spi)
{
/* Verify that the CS is deasserted */
orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
+
+ /* Don't deassert CS between the direct mapped SPI transfers */
+ writel(0, spi_reg(orion_spi, SPI_DIRECT_WRITE_CONFIG_REG));
+
return 0;
}
@@ -504,6 +539,7 @@ static int orion_spi_probe(struct platform_device *pdev)
struct resource *r;
unsigned long tclk_hz;
int status = 0;
+ struct device_node *np;
master = spi_alloc_master(&pdev->dev, sizeof(*spi));
if (master == NULL) {
@@ -576,6 +612,49 @@ static int orion_spi_probe(struct platform_device *pdev)
goto out_rel_clk;
}
+ /* Scan all SPI devices of this controller for direct mapped devices */
+ for_each_available_child_of_node(pdev->dev.of_node, np) {
+ u32 cs;
+
+ /* Get chip-select number from the "reg" property */
+ status = of_property_read_u32(np, "reg", &cs);
+ if (status) {
+ dev_err(&pdev->dev,
+ "%s has no valid 'reg' property (%d)\n",
+ np->full_name, status);
+ status = 0;
+ continue;
+ }
+
+ /*
+ * Check if an address is configured for this SPI device. If
+ * not, the MBus mapping via the 'ranges' property in the 'soc'
+ * node is not configured and this device should not use the
+ * direct mode. In this case, just continue with the next
+ * device.
+ */
+ status = of_address_to_resource(pdev->dev.of_node, cs + 1, r);
+ if (status)
+ continue;
+
+ /*
+ * Only map one page for direct access. This is enough for the
+ * simple TX transfer which only writes to the first word.
+ * This needs to get extended for the direct SPI-NOR / SPI-NAND
+ * support, once this gets implemented.
+ */
+ spi->direct_access[cs].vaddr = devm_ioremap(&pdev->dev,
+ r->start,
+ PAGE_SIZE);
+ if (IS_ERR(spi->direct_access[cs].vaddr)) {
+ status = PTR_ERR(spi->direct_access[cs].vaddr);
+ goto out_rel_clk;
+ }
+ spi->direct_access[cs].size = PAGE_SIZE;
+
+ dev_info(&pdev->dev, "CS%d configured for direct access\n", cs);
+ }
+
pm_runtime_set_active(&pdev->dev);
pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
--
2.8.1
More information about the linux-arm-kernel
mailing list