[PATCH v5 1/2] of: add J-Core SPI master bindings

[PATCH v5 1/2] of: add J-Core SPI master bindings

[Rich Felker]

Signed-off-by: Rich Felker <dalias-8zAoT0mYgF4@public.gmane.org>
---
 .../devicetree/bindings/spi/jcore,spi.txt          | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/jcore,spi.txt

diff --git a/Documentation/devicetree/bindings/spi/jcore,spi.txt b/Documentation/devicetree/bindings/spi/jcore,spi.txt
new file mode 100644
index 0000000..93936d1
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/jcore,spi.txt
@@ -0,0 +1,34 @@
+J-Core SPI master
+
+Required properties:
+
+- compatible: Must be "jcore,spi2".
+
+- reg: Memory region for registers.
+
+- #address-cells: Must be 1.
+
+- #size-cells: Must be 0.
+
+Optional properties:
+
+- clocks: If a phandle named "ref_clk" is present, SPI clock speed
+  programming is relative to the frequency of the indicated clock.
+  Necessary only if the input clock rate is something other than a
+  fixed 50 MHz.
+
+- clock-names: Clock names, one for each phandle in clocks.
+
+See spi-bus.txt for additional properties not specific to this device.
+
+Example:
+
+spi@40 {
+	compatible = "jcore,spi2";
+	#address-cells = <1>;
+	#size-cells = <0>;
+	reg = <0x40 0x8>;
+	spi-max-frequency = <25000000>;
+	clocks = <&bus_clk>;
+	clock-names = "ref_clk";
+}
-- 
2.8.1


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[PATCH v5 2/2] spi: add driver for J-Core SPI controller

[Rich Felker]

The J-Core "spi2" device is a PIO-based SPI master controller. It
differs from "bitbang" devices in that that it's clocked in hardware
rather than via soft clock modulation over gpio, and performs
byte-at-a-time transfers between the cpu and SPI controller.

This driver will be extended to support future versions of the J-Core
SPI controller with DMA transfers when they become available.

Signed-off-by: Rich Felker <dalias-8zAoT0mYgF4@public.gmane.org>
---
 drivers/spi/Kconfig     |   7 ++
 drivers/spi/Makefile    |   1 +
 drivers/spi/spi-jcore.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 240 insertions(+)
 create mode 100644 drivers/spi/spi-jcore.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index d6fb8d4..1abb3d7 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -285,6 +285,13 @@ config SPI_IMX
 	  This enables using the Freescale i.MX SPI controllers in master
 	  mode.
 
+config SPI_JCORE
+	tristate "J-Core SPI Master"
+	depends on OF && (SUPERH || COMPILE_TEST)
+	help
+	  This enables support for the SPI master controller in the J-Core
+	  synthesizable, open source SoC.
+
 config SPI_LM70_LLP
 	tristate "Parallel port adapter for LM70 eval board (DEVELOPMENT)"
 	depends on PARPORT
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 185367e..8715fec 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_SPI_FSL_SPI)		+= spi-fsl-spi.o
 obj-$(CONFIG_SPI_GPIO)			+= spi-gpio.o
 obj-$(CONFIG_SPI_IMG_SPFI)		+= spi-img-spfi.o
 obj-$(CONFIG_SPI_IMX)			+= spi-imx.o
+obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
 obj-$(CONFIG_SPI_LP8841_RTC)		+= spi-lp8841-rtc.o
 obj-$(CONFIG_SPI_MESON_SPIFC)		+= spi-meson-spifc.o
diff --git a/drivers/spi/spi-jcore.c b/drivers/spi/spi-jcore.c
new file mode 100644
index 0000000..7d2044a
--- /dev/null
+++ b/drivers/spi/spi-jcore.c
@@ -0,0 +1,232 @@
+/*
+ * J-Core SPI controller driver
+ *
+ * Copyright (C) 2012-2016 Smart Energy Instruments, Inc.
+ *
+ * Current version by Rich Felker
+ * Based loosely on initial version by Oleksandr G Zhadan
+ *
+ */
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/delay.h>
+
+#define DRV_NAME	"jcore_spi"
+
+#define CTRL_REG	0x0
+#define DATA_REG	0x4
+
+#define JCORE_SPI_CTRL_XMIT		0x02
+#define JCORE_SPI_STAT_BUSY		0x02
+#define JCORE_SPI_CTRL_LOOP		0x08
+#define JCORE_SPI_CTRL_CS_BITS		0x15
+
+#define JCORE_SPI_WAIT_RDY_MAX_LOOP	2000000
+
+struct jcore_spi {
+	struct spi_master *master;
+	void __iomem *base;
+	unsigned int cs_reg;
+	unsigned int speed_reg;
+	unsigned int speed_hz;
+	unsigned int clock_freq;
+};
+
+static int jcore_spi_wait(void __iomem *ctrl_reg)
+{
+	unsigned timeout = JCORE_SPI_WAIT_RDY_MAX_LOOP;
+
+	do {
+		if (!(readl(ctrl_reg) & JCORE_SPI_STAT_BUSY))
+			return 0;
+		cpu_relax();
+	} while (--timeout);
+
+	return -EBUSY;
+}
+
+static void jcore_spi_program(struct jcore_spi *hw)
+{
+	void __iomem *ctrl_reg = hw->base + CTRL_REG;
+
+	if (jcore_spi_wait(ctrl_reg))
+		dev_err(hw->master->dev.parent,
+			"timeout waiting to program ctrl reg.\n");
+
+	writel(hw->cs_reg | hw->speed_reg, ctrl_reg);
+}
+
+static void jcore_spi_chipsel(struct spi_device *spi, bool value)
+{
+	struct jcore_spi *hw = spi_master_get_devdata(spi->master);
+	u32 csbit = 1U << (2 * spi->chip_select);
+
+	dev_dbg(hw->master->dev.parent, "chipselect %d\n", spi->chip_select);
+
+	if (value)
+		hw->cs_reg |= csbit;
+	else
+		hw->cs_reg &= ~csbit;
+
+	jcore_spi_program(hw);
+}
+
+static void jcore_spi_baudrate(struct jcore_spi *hw, int speed)
+{
+	if (speed == hw->speed_hz) return;
+	hw->speed_hz = speed;
+	if (speed >= hw->clock_freq / 2)
+		hw->speed_reg = 0;
+	else
+		hw->speed_reg = ((hw->clock_freq / 2 / speed) - 1) << 27;
+	jcore_spi_program(hw);
+	dev_dbg(hw->master->dev.parent, "speed=%d reg=0x%x\n",
+		speed, hw->speed_reg);
+}
+
+static int jcore_spi_txrx(struct spi_master *master, struct spi_device *spi,
+			  struct spi_transfer *t)
+{
+	struct jcore_spi *hw = spi_master_get_devdata(master);
+
+	void __iomem *ctrl_reg = hw->base + CTRL_REG;
+	void __iomem *data_reg = hw->base + DATA_REG;
+	u32 xmit;
+
+	/* data buffers */
+	const unsigned char *tx;
+	unsigned char *rx;
+	unsigned int len;
+	unsigned int count;
+
+	jcore_spi_baudrate(hw, t->speed_hz);
+
+	xmit = hw->cs_reg | hw->speed_reg | JCORE_SPI_CTRL_XMIT;
+	tx = t->tx_buf;
+	rx = t->rx_buf;
+	len = t->len;
+
+	for (count = 0; count < len; count++) {
+		if (jcore_spi_wait(ctrl_reg))
+			break;
+
+		writel(tx ? *tx++ : 0, data_reg);
+		writel(xmit, ctrl_reg);
+
+		if (jcore_spi_wait(ctrl_reg))
+			break;
+
+		if (rx)
+			*rx++ = readl(data_reg);
+	}
+
+	spi_finalize_current_transfer(master);
+
+	if (count < len)
+		return -EREMOTEIO;
+
+	return 0;
+}
+
+static int jcore_spi_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct jcore_spi *hw;
+	struct spi_master *master;
+	struct resource *res;
+	u32 clock_freq;
+	struct clk *clk;
+	int err = -ENODEV;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct jcore_spi));
+	if (!master)
+		return err;
+
+	/* Setup the master state. */
+	master->num_chipselect = 3;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	master->transfer_one = jcore_spi_txrx;
+	master->set_cs = jcore_spi_chipsel;
+	master->dev.of_node = node;
+	master->bus_num = pdev->id;
+
+	hw = spi_master_get_devdata(master);
+	hw->master = master;
+	platform_set_drvdata(pdev, hw);
+
+	/* Find and map our resources */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		goto exit_busy;
+	if (!devm_request_mem_region(&pdev->dev, res->start,
+				     resource_size(res), pdev->name))
+		goto exit_busy;
+	hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
+					resource_size(res));
+	if (!hw->base)
+		goto exit_busy;
+
+	/*
+	 * The SPI clock rate controlled via a configurable clock divider
+	 * which is applied to the reference clock. A 50 MHz reference is
+	 * most suitable for obtaining standard SPI clock rates, but some
+	 * designs may have a different reference clock, and the DT must
+	 * make the driver aware so that it can properly program the
+	 * requested rate. If the clock is omitted, 50 MHz is assumed.
+	 */
+	clock_freq = 50000000;
+	clk = devm_clk_get(&pdev->dev, "ref_clk");
+	if (!IS_ERR_OR_NULL(clk)) {
+		if (clk_enable(clk) == 0)
+			clock_freq = clk_get_rate(clk);
+		else
+			dev_warn(&pdev->dev, "could not enable ref_clk\n");
+	}
+	hw->clock_freq = clock_freq;
+
+	/* Initialize all CS bits to high. */
+	hw->cs_reg = JCORE_SPI_CTRL_CS_BITS;
+	jcore_spi_baudrate(hw, 400000);
+
+	/* Register our spi controller */
+	err = devm_spi_register_master(&pdev->dev, master);
+	if (err)
+		goto exit;
+
+	return 0;
+
+exit_busy:
+	err = -EBUSY;
+exit:
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(master);
+	return err;
+}
+
+static const struct of_device_id jcore_spi_of_match[] = {
+	{ .compatible = "jcore,spi2" },
+	{},
+};
+
+static struct platform_driver jcore_spi_driver = {
+	.probe = jcore_spi_probe,
+	.driver = {
+		.name = DRV_NAME,
+		.of_match_table = jcore_spi_of_match,
+	},
+};
+
+module_platform_driver(jcore_spi_driver);
+
+MODULE_DESCRIPTION("J-Core SPI driver");
+MODULE_AUTHOR("Rich Felker <dalias-8zAoT0mYgF4@public.gmane.org>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
-- 
2.8.1

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[PATCH v5 0/2] J-Core SPI controller support

[Rich Felker]

Updates based on requests by Mark Brown. Driver has been made
conditional in Kconfig to avoid it showing up in configurations where
it's not relevant. Lots of small style improvements have been made,
and the input clock frequency is now handled via the clk framework
rather than a fixed clock-frequency property in the DT. Corresponding
changes were made to the DT binding patch.

Rich



Rich Felker (2):
  of: add J-Core SPI master bindings
  spi: add driver for J-Core SPI controller

 .../devicetree/bindings/spi/jcore,spi.txt          |  34 +++
 drivers/spi/Kconfig                                |   7 +
 drivers/spi/Makefile                               |   1 +
 drivers/spi/spi-jcore.c                            | 232 +++++++++++++++++++++
 4 files changed, 274 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/jcore,spi.txt
 create mode 100644 drivers/spi/spi-jcore.c

-- 
2.8.1

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Re: [PATCH v5 1/2] of: add J-Core SPI master bindings

[Rob Herring]

On Thu, Aug 04, 2016 at 04:30:37AM +0000, Rich Felker wrote:
> Signed-off-by: Rich Felker <dalias-8zAoT0mYgF4@public.gmane.org>
> ---
>  .../devicetree/bindings/spi/jcore,spi.txt          | 34 ++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/spi/jcore,spi.txt

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
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[PATCH v5 0/2] J-Core SPI controller support

[Rich Felker]

Updates based on requests by Mark Brown. Driver has been made
conditional in Kconfig to avoid it showing up in configurations where
it's not relevant. Lots of small style improvements have been made,
and the input clock frequency is now handled via the clk framework
rather than a fixed clock-frequency property in the DT. Corresponding
changes were made to the DT binding patch.

Rich



Rich Felker (2):
  of: add J-Core SPI master bindings
  spi: add driver for J-Core SPI controller

 .../devicetree/bindings/spi/jcore,spi.txt          |  34 +++
 drivers/spi/Kconfig                                |   7 +
 drivers/spi/Makefile                               |   1 +
 drivers/spi/spi-jcore.c                            | 232 +++++++++++++++++++++
 4 files changed, 274 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/jcore,spi.txt
 create mode 100644 drivers/spi/spi-jcore.c

-- 
2.8.1

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