[PATCH V9 0/4] i2c: ls2x: Add support for the Loongson-2K/LS7A I2C controller

[PATCH V9 0/4] i2c: ls2x: Add support for the Loongson-2K/LS7A I2C controller

[Binbin Zhou]

Hi all:

This patch series adds support for the I2C module found on various
Loongson systems with the Loongson-2K SoC or the Loongson LS7A bridge chip.

For now, the I2C driver is suitable for DT-based or ACPI-based systems.

I have tested on Loongson-3A5000LA+LS7A1000/LS7A2000, Loongson-2K1000LA
and Loongson-2K0500.

Thanks.

Changes since V8:
- patch (3/4)
  - Refactor the error handling process of the ls2x_i2c_xfer_one();
  - Split comment and code.

Changes since V7:
- patch (3/4)
  - I2C_LS2X should be added to the Kconfig/Makefile in Latin
    alphabetical order.
  - To avoid repeated type conversions, 'struct ls2x_i2c_priv *priv'
    replaces 'struct i2c_adapter *adap' as a function parameter, e.g.
    ls2x_i2c_start();
  - Refactor ls2x_i2c_stop() with readb_poll_timeout(), mainly with
    LS2X_SR_BUSY to indicate the status (success/timeout) of the stop
    command;
  - Remove extra parentheses;
  - For consistency, the variable 'r' in ls2x_i2c_probe() is renamed to
    'ret'.

Changes since V6:
- patch (1/4)
  - Add Reviewed-by tag.
- patch (3/4)
  - GPL-2.0 -> GPL-2.0-only;
  - Add property.h;
  - writew() should be used to operate I2C_LS2X_PRER, and drop the
    suffix of I2C_LS2X_PRER_LO/I2C_LS2X_PRER_HI;
  - Drop ls2x_i2c_priv->dev, for it can be completely replaced by
    'adapter.dev.parent';
  - Reasonable return value handling in ls2x_i2c_xfer_one();
  - Dropping the I2C_M_STOP flag judgment, the stop parameter of
    ls2x_i2c_xfer_one() represents the last msg;
  - Add comments for subsys_initcall();
  - Code formatting, such as dropping unnecessary blank lines.

Changes since V5:
- patch (1/4)
  - Add property.h.
- patch (3/4)
  - Put the ls2x_i2c_reginit() in front of irq requst;
  - Refact ls2x_i2c_adjust_bus_speed: discard the magic value of
    the divider register and LS2X_I2C_FREQ_STD is used to calculate
    the frequency;
  - Drop useless parameters: priv->suspended, and also disable I2C
    interrupts during suspend;
  - Drop ls2x_i2c_remove(), for the adapter will be auto deleted on
    driver detach;
  - Drop MODULE_ALIAS;
  - Code formatting, such as alignment.

Thanks Andy for your comments.

Changes since V4:
- patch (1/4)
  - Drop unneeded headers: of.h;
  - xxx_props -> xxx_properties.
- patch (2/4)
  - Add interrupt headers to fix syntax error found by Rob.
- patch (3/4)
  - Drop atmoic loop in ls2x_i2c_master_xfer(), I have tested it on the
    appropriate environment with no problems;
  - Define the corresponding bits in I2C_LS2X_CTR to avoid magic
    numbers;
  - dev_get_drvdata() is used to get ls2x_i2c_priv() in
    ls2x_i2c_suspend();
  - i2c_add_adapter() -> devm_i2c_add_adapter();
  - SET_SYSTEM_SLEEP_PM_OPS() -> DEFINE_RUNTIME_DEV_PM_OPS();
  - Code formatting, such as alignment.

    Details: https://lore.kernel.org/all/Y4e%2F6KewuHjAluSZ@smile.fi.intel.com/

Changes since V3:
- Addressed all review comments from v3
  - Change the changelog text to make it clearer (1/5);
  - Fix some minor bugs, such as formatting issues (2/5);
  - Fix some formatting issues (3/5);
  - Deep refactoring of code for clarity (4/5).
     Details: https://lore.kernel.org/all/Y4S2cnlAm3YYvZ8E@smile.fi.intel.com/

Thanks to all for their suggestions.

Changes since V2:
- Addressed all review comments from v2
  - Drop of_match_ptr() in i2c-gpio to avoid potential unused warnings
    (1/5);
  - Introduce i2c_gpio_get_props() function as the generic interface
    to get i2c-gpio props from DT or ACPI table (2/5);
  - Refact ls2x i2c code, similar to removing excessive goto tags (4/5).

Thanks to Andy and Mika for their suggestions.

Changes since V1:
- Remove the function of getting the static i2c bus number from ACPI "_UID";
- Fix build warning from kernel test robot.

Binbin Zhou (4):
  i2c: gpio: Add support on ACPI-based system
  dt-bindings: i2c: add Loongson LS2X I2C controller
  i2c: ls2x: Add driver for Loongson-2K/LS7A I2C controller
  LoongArch: Enable LS2X I2C in loongson3_defconfig

 .../bindings/i2c/loongson,ls2x-i2c.yaml       |  51 +++
 arch/loongarch/configs/loongson3_defconfig    |   1 +
 drivers/i2c/busses/Kconfig                    |  11 +
 drivers/i2c/busses/Makefile                   |   1 +
 drivers/i2c/busses/i2c-gpio.c                 |  28 +-
 drivers/i2c/busses/i2c-ls2x.c                 | 381 ++++++++++++++++++
 6 files changed, 463 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/loongson,ls2x-i2c.yaml
 create mode 100644 drivers/i2c/busses/i2c-ls2x.c

-- 
2.31.1

[PATCH V9 1/4] i2c: gpio: Add support on ACPI-based system

[Binbin Zhou]

Add support for the ACPI-based device registration, so that the driver
can be also enabled through ACPI table.

Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 drivers/i2c/busses/i2c-gpio.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
index 0e4385a9bcf7..680936234ef8 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -13,9 +13,9 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
-#include <linux/of.h>
 #include <linux/platform_data/i2c-gpio.h>
 #include <linux/platform_device.h>
+#include <linux/property.h>
 #include <linux/slab.h>
 
 struct i2c_gpio_private_data {
@@ -300,22 +300,23 @@ static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
 static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
 #endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/
 
-static void of_i2c_gpio_get_props(struct device_node *np,
-				  struct i2c_gpio_platform_data *pdata)
+/* Get i2c-gpio properties from DT or ACPI table */
+static void i2c_gpio_get_properties(struct device *dev,
+				     struct i2c_gpio_platform_data *pdata)
 {
 	u32 reg;
 
-	of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay);
+	device_property_read_u32(dev, "i2c-gpio,delay-us", &pdata->udelay);
 
-	if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", &reg))
+	if (!device_property_read_u32(dev, "i2c-gpio,timeout-ms", &reg))
 		pdata->timeout = msecs_to_jiffies(reg);
 
 	pdata->sda_is_open_drain =
-		of_property_read_bool(np, "i2c-gpio,sda-open-drain");
+		device_property_read_bool(dev, "i2c-gpio,sda-open-drain");
 	pdata->scl_is_open_drain =
-		of_property_read_bool(np, "i2c-gpio,scl-open-drain");
+		device_property_read_bool(dev, "i2c-gpio,scl-open-drain");
 	pdata->scl_is_output_only =
-		of_property_read_bool(np, "i2c-gpio,scl-output-only");
+		device_property_read_bool(dev, "i2c-gpio,scl-output-only");
 }
 
 static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
@@ -373,8 +374,8 @@ static int i2c_gpio_probe(struct platform_device *pdev)
 	bit_data = &priv->bit_data;
 	pdata = &priv->pdata;
 
-	if (np) {
-		of_i2c_gpio_get_props(np, pdata);
+	if (dev_fwnode(dev)) {
+		i2c_gpio_get_properties(dev, pdata);
 	} else {
 		/*
 		 * If all platform data settings are zero it is OK
@@ -489,10 +490,17 @@ static const struct of_device_id i2c_gpio_dt_ids[] = {
 
 MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
 
+static const struct acpi_device_id i2c_gpio_acpi_match[] = {
+	{ "LOON0005" }, /* LoongArch */
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, i2c_gpio_acpi_match);
+
 static struct platform_driver i2c_gpio_driver = {
 	.driver		= {
 		.name	= "i2c-gpio",
 		.of_match_table	= i2c_gpio_dt_ids,
+		.acpi_match_table = i2c_gpio_acpi_match,
 	},
 	.probe		= i2c_gpio_probe,
 	.remove		= i2c_gpio_remove,
-- 
2.31.1

[PATCH V9 2/4] dt-bindings: i2c: Add Loongson LS2X I2C controller

[Binbin Zhou]

Add Loongson LS2X I2C controller binding with DT schema format using
json-schema.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 .../bindings/i2c/loongson,ls2x-i2c.yaml       | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/loongson,ls2x-i2c.yaml

diff --git a/Documentation/devicetree/bindings/i2c/loongson,ls2x-i2c.yaml b/Documentation/devicetree/bindings/i2c/loongson,ls2x-i2c.yaml
new file mode 100644
index 000000000000..67882ec6e06a
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/loongson,ls2x-i2c.yaml
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/loongson,ls2x-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Loongson LS2X I2C Controller
+
+maintainers:
+  - Binbin Zhou <zhoubinbin@loongson.cn>
+
+allOf:
+  - $ref: /schemas/i2c/i2c-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - loongson,ls2k-i2c
+      - loongson,ls7a-i2c
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c0: i2c@1fe21000 {
+        compatible = "loongson,ls2k-i2c";
+        reg = <0x1fe21000 0x8>;
+        interrupt-parent = <&extioiic>;
+        interrupts = <22 IRQ_TYPE_LEVEL_LOW>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        eeprom@57 {
+            compatible = "atmel,24c16";
+            reg = <0x57>;
+            pagesize = <16>;
+        };
+    };
-- 
2.31.1

[PATCH V9 3/4] i2c: ls2x: Add driver for Loongson-2K/LS7A I2C controller

[Binbin Zhou]

This I2C module is integrated into the Loongson-2K SoCs and Loongson
LS7A bridge chip.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 drivers/i2c/busses/Kconfig    |  11 +
 drivers/i2c/busses/Makefile   |   1 +
 drivers/i2c/busses/i2c-ls2x.c | 381 ++++++++++++++++++++++++++++++++++
 3 files changed, 393 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-ls2x.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e50f9603d189..d80c938142f5 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -761,6 +761,17 @@ config I2C_LPC2K
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-lpc2k.
 
+config I2C_LS2X
+	tristate "Loongson LS2X I2C adapter"
+	depends on MACH_LOONGSON64 || COMPILE_TEST
+	help
+	  If you say yes to this option, support will be included for the
+	  I2C interface on the Loongson-2K SoCs and Loongson LS7A bridge
+	  chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called i2c-ls2x.
+
 config I2C_MLXBF
         tristate "Mellanox BlueField I2C controller"
         depends on MELLANOX_PLATFORM && ARM64
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index e73cdb1d2b5a..0584fe160824 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -77,6 +77,7 @@ obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_JZ4780)	+= i2c-jz4780.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
 obj-$(CONFIG_I2C_LPC2K)		+= i2c-lpc2k.o
+obj-$(CONFIG_I2C_LS2X)		+= i2c-ls2x.o
 obj-$(CONFIG_I2C_MESON)		+= i2c-meson.o
 obj-$(CONFIG_I2C_MICROCHIP_CORE)	+= i2c-microchip-corei2c.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
diff --git a/drivers/i2c/busses/i2c-ls2x.c b/drivers/i2c/busses/i2c-ls2x.c
new file mode 100644
index 000000000000..2215aa04233b
--- /dev/null
+++ b/drivers/i2c/busses/i2c-ls2x.c
@@ -0,0 +1,382 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Loongson-2K/Loongson LS7A I2C master mode driver
+ *
+ * Copyright (C) 2013 Loongson Technology Corporation Limited.
+ * Copyright (C) 2014-2017 Lemote, Inc.
+ * Copyright (C) 2018-2022 Loongson Technology Corporation Limited.
+ *
+ * Originally written by liushaozong
+ * Rewritten for mainline by Binbin Zhou <zhoubinbin@loongson.cn>
+ */
+
+#include <linux/bits.h>
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/iopoll.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/units.h>
+
+/* I2C Registers */
+#define I2C_LS2X_PRER		0x0 /* Freq Division Register(16 bits) */
+#define I2C_LS2X_CTR		0x2 /* Control Register */
+#define I2C_LS2X_TXR		0x3 /* Transport Data Register */
+#define I2C_LS2X_RXR		0x3 /* Receive Data Register */
+#define I2C_LS2X_CR		0x4 /* Command Control Register */
+#define I2C_LS2X_SR		0x4 /* State Register */
+
+/* Command Control Register Bit */
+#define LS2X_CR_START		BIT(7) /* Start signal */
+#define LS2X_CR_STOP		BIT(6) /* Stop signal */
+#define LS2X_CR_READ		BIT(5) /* Read signal */
+#define LS2X_CR_WRITE		BIT(4) /* Write signal */
+#define LS2X_CR_ACK		BIT(3) /* Response signal */
+#define LS2X_CR_IACK		BIT(0) /* Interrupt response signal */
+
+/* State Register Bit */
+#define LS2X_SR_NOACK		BIT(7) /* Receive NACK */
+#define LS2X_SR_BUSY		BIT(6) /* Bus busy state */
+#define LS2X_SR_AL		BIT(5) /* Arbitration lost */
+#define LS2X_SR_TIP		BIT(1) /* Transmission state */
+#define LS2X_SR_IF		BIT(0) /* Interrupt flag */
+
+/* Control Register Bit */
+#define LS2X_CTR_EN		BIT(7) /* 0: I2c frequency setting 1: Normal */
+#define LS2X_CTR_IEN		BIT(6) /* Enable i2c interrupt */
+#define LS2X_CTR_MST		BIT(5) /* 0: Slave mode 1: Master mode */
+#define CTR_FREQ_MASK		GENMASK(7, 6)
+#define CTR_READY_MASK		GENMASK(7, 5)
+
+/* The PCLK frequency from LPB */
+#define LS2X_I2C_PCLK_FREQ	(50 * HZ_PER_MHZ)
+
+/* The default bus frequency, which is an empirical value */
+#define LS2X_I2C_FREQ_STD	(33 * HZ_PER_KHZ)
+
+struct ls2x_i2c_priv {
+	struct i2c_adapter	adapter;
+	void __iomem		*base;
+	struct i2c_timings	i2c_t;
+	struct completion	cmd_complete;
+};
+
+/*
+ * Interrupt service routine.
+ * This gets called whenever an I2C interrupt occurs.
+ */
+static irqreturn_t ls2x_i2c_isr(int this_irq, void *dev_id)
+{
+	struct ls2x_i2c_priv *priv = dev_id;
+
+	if (!(readb(priv->base + I2C_LS2X_SR) & LS2X_SR_IF))
+		return IRQ_NONE;
+
+	writeb(LS2X_CR_IACK, priv->base + I2C_LS2X_CR);
+	complete(&priv->cmd_complete);
+	return IRQ_HANDLED;
+}
+
+/*
+ * The ls2x i2c controller supports standard mode and fast mode, so the
+ * maximum bus frequency is '400kHz'.
+ * The bus frequency is set to the empirical value of '33KHz' by default,
+ * but it can also be taken from ACPI or FDT for compatibility with more
+ * devices.
+ */
+static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
+{
+	struct i2c_timings *t = &priv->i2c_t;
+	struct device *dev = priv->adapter.dev.parent;
+	u32 acpi_speed = i2c_acpi_find_bus_speed(dev);
+
+	i2c_parse_fw_timings(dev, t, false);
+
+	if (acpi_speed || t->bus_freq_hz)
+		t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
+	else
+		t->bus_freq_hz = LS2X_I2C_FREQ_STD;
+
+	/* Calculate and set i2c frequency. */
+	writew(LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1,
+	       priv->base + I2C_LS2X_PRER);
+}
+
+static void ls2x_i2c_init(struct ls2x_i2c_priv *priv)
+{
+	/* Set i2c frequency setting mode and disable interrupts. */
+	writeb(readb(priv->base + I2C_LS2X_CTR) & ~CTR_FREQ_MASK,
+	       priv->base + I2C_LS2X_CTR);
+
+	ls2x_i2c_adjust_bus_speed(priv);
+
+	/* Set i2c normal operating mode and enable interrupts. */
+	writeb(readb(priv->base + I2C_LS2X_CTR) | CTR_READY_MASK,
+	       priv->base + I2C_LS2X_CTR);
+}
+
+static int ls2x_i2c_xfer_byte(struct ls2x_i2c_priv *priv, u8 txdata, u8 *rxdatap)
+{
+	u8 rxdata;
+	unsigned long time_left;
+
+	writeb(txdata, priv->base + I2C_LS2X_CR);
+
+	time_left = wait_for_completion_timeout(&priv->cmd_complete,
+						priv->adapter.timeout);
+	if (!time_left)
+		return -ETIMEDOUT;
+
+	rxdata = readb(priv->base + I2C_LS2X_SR);
+	if (rxdatap)
+		*rxdatap = rxdata;
+
+	return 0;
+}
+
+static int ls2x_i2c_send_byte(struct ls2x_i2c_priv *priv, u8 txdata)
+{
+	int ret;
+	u8 rxdata;
+
+	ret = ls2x_i2c_xfer_byte(priv, txdata, &rxdata);
+	if (ret)
+		return ret;
+
+	if (rxdata & LS2X_SR_AL)
+		return -EAGAIN;
+
+	if (rxdata & LS2X_SR_NOACK)
+		return -ENXIO;
+
+	return 0;
+}
+
+static int ls2x_i2c_stop(struct ls2x_i2c_priv *priv)
+{
+	u8 value;
+
+	writeb(LS2X_CR_STOP, priv->base + I2C_LS2X_CR);
+	return readb_poll_timeout(priv->base + I2C_LS2X_SR, value,
+				  !(value & LS2X_SR_BUSY), 100,
+				  jiffies_to_usecs(priv->adapter.timeout));
+}
+
+static int ls2x_i2c_start(struct ls2x_i2c_priv *priv, struct i2c_msg *msgs)
+{
+	reinit_completion(&priv->cmd_complete);
+
+	writeb(i2c_8bit_addr_from_msg(msgs), priv->base + I2C_LS2X_TXR);
+	return ls2x_i2c_send_byte(priv, LS2X_CR_START | LS2X_CR_WRITE);
+}
+
+static int ls2x_i2c_rx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
+{
+	int ret;
+	u8 rxdata, *buf = msg->buf;
+	u16 len = msg->len;
+
+	/* Contains steps to send start condition and address. */
+	ret = ls2x_i2c_start(priv, msg);
+	if (ret)
+		return ret;
+
+	while (len--) {
+		ret = ls2x_i2c_xfer_byte(priv,
+					 LS2X_CR_READ | (len ? 0 : LS2X_CR_ACK),
+					 &rxdata);
+		if (ret)
+			return ret;
+
+		*buf++ = readb(priv->base + I2C_LS2X_RXR);
+	}
+
+	return 0;
+}
+
+static int ls2x_i2c_tx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
+{
+	int ret;
+	u8 *buf = msg->buf;
+	u16 len = msg->len;
+
+	/* Contains steps to send start condition and address. */
+	ret = ls2x_i2c_start(priv, msg);
+	if (ret)
+		return ret;
+
+	while (len--) {
+		writeb(*buf++, priv->base + I2C_LS2X_TXR);
+
+		ret = ls2x_i2c_send_byte(priv, LS2X_CR_WRITE);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int ls2x_i2c_xfer_one(struct ls2x_i2c_priv *priv,
+			     struct i2c_msg *msg, bool stop)
+{
+	int ret;
+
+	if (msg->flags & I2C_M_RD)
+		ret = ls2x_i2c_rx(priv, msg);
+	else
+		ret = ls2x_i2c_tx(priv, msg);
+
+	if (ret < 0) {
+		/* Fatel error. Needs reinit. */
+		if (ret == -ETIMEDOUT)
+			ls2x_i2c_init(priv);
+
+		return ret;
+	}
+
+	if (stop) {
+		/* Failed to issue STOP. Needs reinit. */
+		ret = ls2x_i2c_stop(priv);
+		if (ret)
+			ls2x_i2c_init(priv);
+	}
+
+	return ret;
+}
+
+static int ls2x_i2c_master_xfer(struct i2c_adapter *adap,
+				struct i2c_msg *msgs, int num)
+{
+	int ret;
+	struct i2c_msg *msg, *emsg = msgs + num;
+	struct ls2x_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	for (msg = msgs; msg < emsg; msg++) {
+		ret = ls2x_i2c_xfer_one(priv, msg, msg == emsg - 1);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static unsigned int ls2x_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm ls2x_i2c_algo = {
+	.master_xfer	= ls2x_i2c_master_xfer,
+	.functionality	= ls2x_i2c_func,
+};
+
+static int ls2x_i2c_probe(struct platform_device *pdev)
+{
+	int ret, irq;
+	struct i2c_adapter *adap;
+	struct ls2x_i2c_priv *priv;
+	struct device *dev = &pdev->dev;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	/* Map hardware registers */
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	/* Add the i2c adapter */
+	adap = &priv->adapter;
+	adap->retries = 5;
+	adap->nr = pdev->id;
+	adap->dev.parent = dev;
+	adap->owner = THIS_MODULE;
+	adap->algo = &ls2x_i2c_algo;
+	adap->timeout = msecs_to_jiffies(100);
+	device_set_node(&adap->dev, dev_fwnode(dev));
+	i2c_set_adapdata(adap, priv);
+	strscpy(adap->name, pdev->name, sizeof(adap->name));
+	init_completion(&priv->cmd_complete);
+	platform_set_drvdata(pdev, priv);
+
+	ls2x_i2c_init(priv);
+
+	ret = devm_request_irq(dev, irq, ls2x_i2c_isr, IRQF_SHARED, "ls2x-i2c",
+			       priv);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);
+
+	return devm_i2c_add_adapter(dev, adap);
+}
+
+static int ls2x_i2c_suspend(struct device *dev)
+{
+	struct ls2x_i2c_priv *priv = dev_get_drvdata(dev);
+
+	/* Disable interrupts */
+	writeb(readb(priv->base + I2C_LS2X_CTR) & ~LS2X_CTR_IEN,
+	       priv->base + I2C_LS2X_CTR);
+
+	return 0;
+}
+
+static int ls2x_i2c_resume(struct device *dev)
+{
+	ls2x_i2c_init(dev_get_drvdata(dev));
+	return 0;
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(ls2x_i2c_pm_ops,
+				 ls2x_i2c_suspend, ls2x_i2c_resume, NULL);
+
+static const struct of_device_id ls2x_i2c_id_table[] = {
+	{ .compatible = "loongson,ls2k-i2c" },
+	{ .compatible = "loongson,ls7a-i2c" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ls2x_i2c_id_table);
+
+static const struct acpi_device_id ls2x_i2c_acpi_match[] = {
+	{ "LOON0004" }, /* Loongson LS7A */
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, ls2x_i2c_acpi_match);
+
+static struct platform_driver ls2x_i2c_driver = {
+	.probe		= ls2x_i2c_probe,
+	.driver		= {
+		.name	= "ls2x-i2c",
+		.pm	= pm_sleep_ptr(&ls2x_i2c_pm_ops),
+		.of_match_table = ls2x_i2c_id_table,
+		.acpi_match_table = ls2x_i2c_acpi_match,
+	},
+};
+
+/* The DC subsystem depends on it, we should initialize it earlier. */
+static int __init ls2x_i2c_init_driver(void)
+{
+	return platform_driver_register(&ls2x_i2c_driver);
+}
+subsys_initcall(ls2x_i2c_init_driver);
+
+static void __exit ls2x_i2c_exit_driver(void)
+{
+	platform_driver_unregister(&ls2x_i2c_driver);
+}
+module_exit(ls2x_i2c_exit_driver);
+
+MODULE_DESCRIPTION("Loongson LS2X I2C Bus driver");
+MODULE_AUTHOR("Loongson Technology Corporation Limited");
+MODULE_LICENSE("GPL");
-- 
2.31.1

Re: [PATCH V9 3/4] i2c: ls2x: Add driver for Loongson-2K/LS7A I2C controller

[Andy Shevchenko]

On Tue, Jan 03, 2023 at 03:00:47PM +0800, Binbin Zhou wrote:
> This I2C module is integrated into the Loongson-2K SoCs and Loongson
> LS7A bridge chip.

I believe that you have tested this on real hardware and it works as expected.
From the code perspective it is good to me,
Reviewed-by: Andy Shevchenko <andy@kernel.org>

> Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
> ---
>  drivers/i2c/busses/Kconfig    |  11 +
>  drivers/i2c/busses/Makefile   |   1 +
>  drivers/i2c/busses/i2c-ls2x.c | 381 ++++++++++++++++++++++++++++++++++
>  3 files changed, 393 insertions(+)
>  create mode 100644 drivers/i2c/busses/i2c-ls2x.c
> 
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index e50f9603d189..d80c938142f5 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -761,6 +761,17 @@ config I2C_LPC2K
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called i2c-lpc2k.
>  
> +config I2C_LS2X
> +	tristate "Loongson LS2X I2C adapter"
> +	depends on MACH_LOONGSON64 || COMPILE_TEST
> +	help
> +	  If you say yes to this option, support will be included for the
> +	  I2C interface on the Loongson-2K SoCs and Loongson LS7A bridge
> +	  chip.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called i2c-ls2x.
> +
>  config I2C_MLXBF
>          tristate "Mellanox BlueField I2C controller"
>          depends on MELLANOX_PLATFORM && ARM64
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index e73cdb1d2b5a..0584fe160824 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -77,6 +77,7 @@ obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
>  obj-$(CONFIG_I2C_JZ4780)	+= i2c-jz4780.o
>  obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
>  obj-$(CONFIG_I2C_LPC2K)		+= i2c-lpc2k.o
> +obj-$(CONFIG_I2C_LS2X)		+= i2c-ls2x.o
>  obj-$(CONFIG_I2C_MESON)		+= i2c-meson.o
>  obj-$(CONFIG_I2C_MICROCHIP_CORE)	+= i2c-microchip-corei2c.o
>  obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
> diff --git a/drivers/i2c/busses/i2c-ls2x.c b/drivers/i2c/busses/i2c-ls2x.c
> new file mode 100644
> index 000000000000..2215aa04233b
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-ls2x.c
> @@ -0,0 +1,382 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Loongson-2K/Loongson LS7A I2C master mode driver
> + *
> + * Copyright (C) 2013 Loongson Technology Corporation Limited.
> + * Copyright (C) 2014-2017 Lemote, Inc.
> + * Copyright (C) 2018-2022 Loongson Technology Corporation Limited.
> + *
> + * Originally written by liushaozong
> + * Rewritten for mainline by Binbin Zhou <zhoubinbin@loongson.cn>
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/completion.h>
> +#include <linux/device.h>
> +#include <linux/iopoll.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/units.h>
> +
> +/* I2C Registers */
> +#define I2C_LS2X_PRER		0x0 /* Freq Division Register(16 bits) */
> +#define I2C_LS2X_CTR		0x2 /* Control Register */
> +#define I2C_LS2X_TXR		0x3 /* Transport Data Register */
> +#define I2C_LS2X_RXR		0x3 /* Receive Data Register */
> +#define I2C_LS2X_CR		0x4 /* Command Control Register */
> +#define I2C_LS2X_SR		0x4 /* State Register */
> +
> +/* Command Control Register Bit */
> +#define LS2X_CR_START		BIT(7) /* Start signal */
> +#define LS2X_CR_STOP		BIT(6) /* Stop signal */
> +#define LS2X_CR_READ		BIT(5) /* Read signal */
> +#define LS2X_CR_WRITE		BIT(4) /* Write signal */
> +#define LS2X_CR_ACK		BIT(3) /* Response signal */
> +#define LS2X_CR_IACK		BIT(0) /* Interrupt response signal */
> +
> +/* State Register Bit */
> +#define LS2X_SR_NOACK		BIT(7) /* Receive NACK */
> +#define LS2X_SR_BUSY		BIT(6) /* Bus busy state */
> +#define LS2X_SR_AL		BIT(5) /* Arbitration lost */
> +#define LS2X_SR_TIP		BIT(1) /* Transmission state */
> +#define LS2X_SR_IF		BIT(0) /* Interrupt flag */
> +
> +/* Control Register Bit */
> +#define LS2X_CTR_EN		BIT(7) /* 0: I2c frequency setting 1: Normal */
> +#define LS2X_CTR_IEN		BIT(6) /* Enable i2c interrupt */
> +#define LS2X_CTR_MST		BIT(5) /* 0: Slave mode 1: Master mode */
> +#define CTR_FREQ_MASK		GENMASK(7, 6)
> +#define CTR_READY_MASK		GENMASK(7, 5)
> +
> +/* The PCLK frequency from LPB */
> +#define LS2X_I2C_PCLK_FREQ	(50 * HZ_PER_MHZ)
> +
> +/* The default bus frequency, which is an empirical value */
> +#define LS2X_I2C_FREQ_STD	(33 * HZ_PER_KHZ)
> +
> +struct ls2x_i2c_priv {
> +	struct i2c_adapter	adapter;
> +	void __iomem		*base;
> +	struct i2c_timings	i2c_t;
> +	struct completion	cmd_complete;
> +};
> +
> +/*
> + * Interrupt service routine.
> + * This gets called whenever an I2C interrupt occurs.
> + */
> +static irqreturn_t ls2x_i2c_isr(int this_irq, void *dev_id)
> +{
> +	struct ls2x_i2c_priv *priv = dev_id;
> +
> +	if (!(readb(priv->base + I2C_LS2X_SR) & LS2X_SR_IF))
> +		return IRQ_NONE;
> +
> +	writeb(LS2X_CR_IACK, priv->base + I2C_LS2X_CR);
> +	complete(&priv->cmd_complete);
> +	return IRQ_HANDLED;
> +}
> +
> +/*
> + * The ls2x i2c controller supports standard mode and fast mode, so the
> + * maximum bus frequency is '400kHz'.
> + * The bus frequency is set to the empirical value of '33KHz' by default,
> + * but it can also be taken from ACPI or FDT for compatibility with more
> + * devices.
> + */
> +static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
> +{
> +	struct i2c_timings *t = &priv->i2c_t;
> +	struct device *dev = priv->adapter.dev.parent;
> +	u32 acpi_speed = i2c_acpi_find_bus_speed(dev);
> +
> +	i2c_parse_fw_timings(dev, t, false);
> +
> +	if (acpi_speed || t->bus_freq_hz)
> +		t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
> +	else
> +		t->bus_freq_hz = LS2X_I2C_FREQ_STD;
> +
> +	/* Calculate and set i2c frequency. */
> +	writew(LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1,
> +	       priv->base + I2C_LS2X_PRER);
> +}
> +
> +static void ls2x_i2c_init(struct ls2x_i2c_priv *priv)
> +{
> +	/* Set i2c frequency setting mode and disable interrupts. */
> +	writeb(readb(priv->base + I2C_LS2X_CTR) & ~CTR_FREQ_MASK,
> +	       priv->base + I2C_LS2X_CTR);
> +
> +	ls2x_i2c_adjust_bus_speed(priv);
> +
> +	/* Set i2c normal operating mode and enable interrupts. */
> +	writeb(readb(priv->base + I2C_LS2X_CTR) | CTR_READY_MASK,
> +	       priv->base + I2C_LS2X_CTR);
> +}
> +
> +static int ls2x_i2c_xfer_byte(struct ls2x_i2c_priv *priv, u8 txdata, u8 *rxdatap)
> +{
> +	u8 rxdata;
> +	unsigned long time_left;
> +
> +	writeb(txdata, priv->base + I2C_LS2X_CR);
> +
> +	time_left = wait_for_completion_timeout(&priv->cmd_complete,
> +						priv->adapter.timeout);
> +	if (!time_left)
> +		return -ETIMEDOUT;
> +
> +	rxdata = readb(priv->base + I2C_LS2X_SR);
> +	if (rxdatap)
> +		*rxdatap = rxdata;
> +
> +	return 0;
> +}
> +
> +static int ls2x_i2c_send_byte(struct ls2x_i2c_priv *priv, u8 txdata)
> +{
> +	int ret;
> +	u8 rxdata;
> +
> +	ret = ls2x_i2c_xfer_byte(priv, txdata, &rxdata);
> +	if (ret)
> +		return ret;
> +
> +	if (rxdata & LS2X_SR_AL)
> +		return -EAGAIN;
> +
> +	if (rxdata & LS2X_SR_NOACK)
> +		return -ENXIO;
> +
> +	return 0;
> +}
> +
> +static int ls2x_i2c_stop(struct ls2x_i2c_priv *priv)
> +{
> +	u8 value;
> +
> +	writeb(LS2X_CR_STOP, priv->base + I2C_LS2X_CR);
> +	return readb_poll_timeout(priv->base + I2C_LS2X_SR, value,
> +				  !(value & LS2X_SR_BUSY), 100,
> +				  jiffies_to_usecs(priv->adapter.timeout));
> +}
> +
> +static int ls2x_i2c_start(struct ls2x_i2c_priv *priv, struct i2c_msg *msgs)
> +{
> +	reinit_completion(&priv->cmd_complete);
> +
> +	writeb(i2c_8bit_addr_from_msg(msgs), priv->base + I2C_LS2X_TXR);
> +	return ls2x_i2c_send_byte(priv, LS2X_CR_START | LS2X_CR_WRITE);
> +}
> +
> +static int ls2x_i2c_rx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
> +{
> +	int ret;
> +	u8 rxdata, *buf = msg->buf;
> +	u16 len = msg->len;
> +
> +	/* Contains steps to send start condition and address. */
> +	ret = ls2x_i2c_start(priv, msg);
> +	if (ret)
> +		return ret;
> +
> +	while (len--) {
> +		ret = ls2x_i2c_xfer_byte(priv,
> +					 LS2X_CR_READ | (len ? 0 : LS2X_CR_ACK),
> +					 &rxdata);
> +		if (ret)
> +			return ret;
> +
> +		*buf++ = readb(priv->base + I2C_LS2X_RXR);
> +	}
> +
> +	return 0;
> +}
> +
> +static int ls2x_i2c_tx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
> +{
> +	int ret;
> +	u8 *buf = msg->buf;
> +	u16 len = msg->len;
> +
> +	/* Contains steps to send start condition and address. */
> +	ret = ls2x_i2c_start(priv, msg);
> +	if (ret)
> +		return ret;
> +
> +	while (len--) {
> +		writeb(*buf++, priv->base + I2C_LS2X_TXR);
> +
> +		ret = ls2x_i2c_send_byte(priv, LS2X_CR_WRITE);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ls2x_i2c_xfer_one(struct ls2x_i2c_priv *priv,
> +			     struct i2c_msg *msg, bool stop)
> +{
> +	int ret;
> +
> +	if (msg->flags & I2C_M_RD)
> +		ret = ls2x_i2c_rx(priv, msg);
> +	else
> +		ret = ls2x_i2c_tx(priv, msg);
> +
> +	if (ret < 0) {
> +		/* Fatel error. Needs reinit. */
> +		if (ret == -ETIMEDOUT)
> +			ls2x_i2c_init(priv);
> +
> +		return ret;
> +	}
> +
> +	if (stop) {
> +		/* Failed to issue STOP. Needs reinit. */
> +		ret = ls2x_i2c_stop(priv);
> +		if (ret)
> +			ls2x_i2c_init(priv);
> +	}
> +
> +	return ret;
> +}
> +
> +static int ls2x_i2c_master_xfer(struct i2c_adapter *adap,
> +				struct i2c_msg *msgs, int num)
> +{
> +	int ret;
> +	struct i2c_msg *msg, *emsg = msgs + num;
> +	struct ls2x_i2c_priv *priv = i2c_get_adapdata(adap);
> +
> +	for (msg = msgs; msg < emsg; msg++) {
> +		ret = ls2x_i2c_xfer_one(priv, msg, msg == emsg - 1);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return num;
> +}
> +
> +static unsigned int ls2x_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static const struct i2c_algorithm ls2x_i2c_algo = {
> +	.master_xfer	= ls2x_i2c_master_xfer,
> +	.functionality	= ls2x_i2c_func,
> +};
> +
> +static int ls2x_i2c_probe(struct platform_device *pdev)
> +{
> +	int ret, irq;
> +	struct i2c_adapter *adap;
> +	struct ls2x_i2c_priv *priv;
> +	struct device *dev = &pdev->dev;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	/* Map hardware registers */
> +	priv->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(priv->base))
> +		return PTR_ERR(priv->base);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return irq;
> +
> +	/* Add the i2c adapter */
> +	adap = &priv->adapter;
> +	adap->retries = 5;
> +	adap->nr = pdev->id;
> +	adap->dev.parent = dev;
> +	adap->owner = THIS_MODULE;
> +	adap->algo = &ls2x_i2c_algo;
> +	adap->timeout = msecs_to_jiffies(100);
> +	device_set_node(&adap->dev, dev_fwnode(dev));
> +	i2c_set_adapdata(adap, priv);
> +	strscpy(adap->name, pdev->name, sizeof(adap->name));
> +	init_completion(&priv->cmd_complete);
> +	platform_set_drvdata(pdev, priv);
> +
> +	ls2x_i2c_init(priv);
> +
> +	ret = devm_request_irq(dev, irq, ls2x_i2c_isr, IRQF_SHARED, "ls2x-i2c",
> +			       priv);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);
> +
> +	return devm_i2c_add_adapter(dev, adap);
> +}
> +
> +static int ls2x_i2c_suspend(struct device *dev)
> +{
> +	struct ls2x_i2c_priv *priv = dev_get_drvdata(dev);
> +
> +	/* Disable interrupts */
> +	writeb(readb(priv->base + I2C_LS2X_CTR) & ~LS2X_CTR_IEN,
> +	       priv->base + I2C_LS2X_CTR);
> +
> +	return 0;
> +}
> +
> +static int ls2x_i2c_resume(struct device *dev)
> +{
> +	ls2x_i2c_init(dev_get_drvdata(dev));
> +	return 0;
> +}
> +
> +static DEFINE_RUNTIME_DEV_PM_OPS(ls2x_i2c_pm_ops,
> +				 ls2x_i2c_suspend, ls2x_i2c_resume, NULL);
> +
> +static const struct of_device_id ls2x_i2c_id_table[] = {
> +	{ .compatible = "loongson,ls2k-i2c" },
> +	{ .compatible = "loongson,ls7a-i2c" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, ls2x_i2c_id_table);
> +
> +static const struct acpi_device_id ls2x_i2c_acpi_match[] = {
> +	{ "LOON0004" }, /* Loongson LS7A */
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, ls2x_i2c_acpi_match);
> +
> +static struct platform_driver ls2x_i2c_driver = {
> +	.probe		= ls2x_i2c_probe,
> +	.driver		= {
> +		.name	= "ls2x-i2c",
> +		.pm	= pm_sleep_ptr(&ls2x_i2c_pm_ops),
> +		.of_match_table = ls2x_i2c_id_table,
> +		.acpi_match_table = ls2x_i2c_acpi_match,
> +	},
> +};
> +
> +/* The DC subsystem depends on it, we should initialize it earlier. */
> +static int __init ls2x_i2c_init_driver(void)
> +{
> +	return platform_driver_register(&ls2x_i2c_driver);
> +}
> +subsys_initcall(ls2x_i2c_init_driver);
> +
> +static void __exit ls2x_i2c_exit_driver(void)
> +{
> +	platform_driver_unregister(&ls2x_i2c_driver);
> +}
> +module_exit(ls2x_i2c_exit_driver);
> +
> +MODULE_DESCRIPTION("Loongson LS2X I2C Bus driver");
> +MODULE_AUTHOR("Loongson Technology Corporation Limited");
> +MODULE_LICENSE("GPL");
> -- 
> 2.31.1
> 

-- 
With Best Regards,
Andy Shevchenko

[PATCH V9 4/4] LoongArch: Enable LS2X I2C in loongson3_defconfig

[Binbin Zhou]

This is now supported, enable for Loongson-3 systems.
Other systems are unaffected.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 arch/loongarch/configs/loongson3_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig
index cb52774c80e8..5677c4f8576e 100644
--- a/arch/loongarch/configs/loongson3_defconfig
+++ b/arch/loongarch/configs/loongson3_defconfig
@@ -602,6 +602,7 @@ CONFIG_HW_RANDOM_VIRTIO=m
 CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_PIIX4=y
 CONFIG_I2C_GPIO=y
+CONFIG_I2C_LS2X=y
 CONFIG_SPI=y
 CONFIG_GPIO_SYSFS=y
 CONFIG_GPIO_LOONGSON=y
-- 
2.31.1