[PATCH RFC 0/5] mfd: ls2kbmc: multiple fixes for this driver

[PATCH RFC 0/5] mfd: ls2kbmc: multiple fixes for this driver

[Miao Wang via B4 Relay]

Previously, the driver has been introduced to support the Loongson 2K
BMC running on the Loongson Servers, which is essential to prevent
the system from hanging when the BMC is being reset and the default
efi-framebuffer is being used. However, there are some drawbacks in the
driver.

Firstly, the driver tries to read and write to the connected PCI-E host
controller registers, assuming that the BMC is connected to LS7A PCI-E
host controller. This assumption should be true for real products, but
to prevent from accidentally reading and writing to the wrong PCI-E host
controller, this driver should be modified to check this before
accessing the registers.

Secondly, the driver uses non-exported functions to tell the vt
subsystem to redraw the screen, preventing the driver from being
compiling as a module. This can be fixed by using the exported
functions instead.

Thirdly, the driver directly accesses the GPIO controller registers
using hard-coded addresses, which might conflict with the loaded GPIO
controller driver for the same GPIO controller. This is fixed in this
series by using the GPIO subsystem APIs instead. However, legacy GPIO
APIs have to be used in this fixed to correctly request a GPIO
descriptor from the GPIO subsystem, which might be further discussed
to find a better solution.

Finally, there is a minor issue in the driver where it changes the
mode string describing the screen resolution during probing, which
prevents the device from being probed again if -EPROBE_DEFER is
returned by the probe function.

I have tested the changes in this series on a single-socket Loongson
3C6000 server with a Loongson 2K BMC, and the driver works as expected
when the corresponding GPIO driver is additionally loaded.

Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
Miao Wang (5):
      mfd: ls2kbmc: make a copy when parsing mode string
      mfd: ls2kbmc: sanity check for the connected pci port
      mfd: ls2kbmc: redraw using exported functions
      mfd: ls2kbmc: able to compile as a module
      mfd: ls2kbmc: capture the reset event of BMC through GPIO

 drivers/mfd/Kconfig         |   2 +-
 drivers/mfd/ls2k-bmc-core.c | 224 ++++++++++++++++++++++++++++++++++----------
 2 files changed, 174 insertions(+), 52 deletions(-)
---
base-commit: 0e35b9b6ec0ffcc5e23cbdec09f5c622ad532b53
change-id: 20260626-ls2kbmc-mod-5209193009b2

Best regards,
-- 
Miao Wang <shankerwangmiao@gmail.com>

[PATCH RFC 1/5] mfd: ls2kbmc: make a copy when parsing mode string

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

When parsing the mode string from BMC, the string is manipulated
in-place with strsep(), preventing from parsing it again. Make a copy of
the original string and manipulate the copy instead to fix this.

Fixes: 0d64f6d1ffe9 ("mfd: ls2kbmc: Introduce Loongson-2K BMC core driver")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index 408056bfb2fe757a5bde43775a483a48352e706d..30b275bc48794a22249aeb8ba805ef78772d3466 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -427,34 +427,53 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
  */
 static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_data *pd)
 {
-	char *mode;
+	/* Assume 1024 bytes is enough for the resolution string */
+	char mode_buf[1024];
+	char *mode = mode_buf;
+	const void __iomem *mode_base;
 	int depth, ret;
 
 	/* The last 16M of PCI BAR0 is used to store the resolution string. */
-	mode = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
-	if (!mode)
+	mode_base = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M,
+				 sizeof(mode_buf));
+	if (!mode_base)
 		return -ENOMEM;
+	memcpy(mode_buf, mode_base, sizeof(mode_buf) - 1);
+	mode_buf[sizeof(mode_buf) - 1] = '\0';
+	devm_iounmap(&pdev->dev, (void __iomem *)mode_base);
 
 	/* The resolution field starts with the flag "video=". */
 	if (!strncmp(mode, "video=", 6))
 		mode = mode + 6;
+	else
+		goto invalid_mode;
 
 	ret = kstrtoint(strsep(&mode, "x"), 10, &pd->width);
 	if (ret)
 		return ret;
+	if (mode == NULL)
+		goto invalid_mode;
 
 	ret = kstrtoint(strsep(&mode, "-"), 10, &pd->height);
 	if (ret)
 		return ret;
+	if (mode == NULL)
+		goto invalid_mode;
 
 	ret = kstrtoint(strsep(&mode, "@"), 10, &depth);
 	if (ret)
 		return ret;
+	if (mode == NULL)
+		goto invalid_mode;
 
 	pd->stride = pd->width * depth / 8;
 	pd->format = depth == 32 ? "a8r8g8b8" : "r5g6b5";
 
 	return 0;
+
+invalid_mode:
+	dev_err(&pdev->dev, "Invalid resolution string: %s\n", mode_buf);
+	return -EINVAL;
 }
 
 static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)

-- 
2.49.0

[PATCH RFC 2/5] mfd: ls2kbmc: sanity check for the connected pci port

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

When the bmc resets, the recovery procedure require to reconfigure the
parent device. The driver assumes that the parent device should be LS7A.
Add a sanity check on initialization to ensure this and prevent from
accidentally operating on non-LS7A ports.

Fixes: d952bba3fbb5 ("mfd: ls2kbmc: Add Loongson-2K BMC reset function support")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index 30b275bc48794a22249aeb8ba805ef78772d3466..39ce5e55ffd6d3a578008dd752b3e8dceec9bd81 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -35,6 +35,15 @@
 #define LS2K_IPMI3_RES_START		(LS2K_IPMI2_RES_START + LS2K_IPMI_RES_SIZE)
 #define LS2K_IPMI4_RES_START		(LS2K_IPMI3_RES_START + LS2K_IPMI_RES_SIZE)
 
+/* LS7A port Device IDs */
+#define DEV_LS7A1K_PCIE_PORT0	0x7a09
+#define DEV_LS7A1K_PCIE_PORT1	0x7a19
+#define DEV_LS7A1K_PCIE_PORT2	0x7a29
+#define DEV_LS7A2K_PCIE_PORT0	0x7a39
+#define DEV_LS7A2K_PCIE_PORT1	0x7a49
+#define DEV_LS7A2K_PCIE_PORT2	0x7a59
+#define DEV_LS7A2K_PCIE_PORT3	0x7a69
+
 #define LS7A_PCI_CFG_SIZE		0x100
 
 /* LS7A bridge registers */
@@ -476,6 +485,24 @@ static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_da
 	return -EINVAL;
 }
 
+static struct pci_device_id ls7a_ports[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A1K_PCIE_PORT0) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A1K_PCIE_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A1K_PCIE_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT0) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT3) },
+	{ }
+};
+
+static bool ls2k_check_parent(struct pci_dev *dev)
+{
+	struct pci_dev *parent = dev->bus->self;
+
+	return pci_match_id(ls7a_ports, parent) != NULL;
+}
+
 static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
 	struct simplefb_platform_data pd;
@@ -487,6 +514,11 @@ static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (ret)
 		return ret;
 
+	if (!ls2k_check_parent(dev)) {
+		dev_err(&dev->dev, "Expected to be connected to LS7A PCI-E port\n");
+		return -ENODEV;
+	}
+
 	ddata = devm_kzalloc(&dev->dev, sizeof(*ddata), GFP_KERNEL);
 	if (!ddata)
 		return -ENOMEM;

-- 
2.49.0

[PATCH RFC 3/5] mfd: ls2kbmc: redraw using exported functions

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

Use update_screen, i.e. redraw_screen() to trigger the redraw of the
current vt.

Fixes: d952bba3fbb5 ("mfd: ls2kbmc: Add Loongson-2K BMC reset function support")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index 39ce5e55ffd6d3a578008dd752b3e8dceec9bd81..4ceae6c70fb27ae2d6a2a92f4f45a376f1cdb699 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -25,6 +25,7 @@
 #include <linux/platform_device.h>
 #include <linux/stop_machine.h>
 #include <linux/vt_kern.h>
+#include <linux/console.h>
 
 /* LS2K BMC resources */
 #define LS2K_DISPLAY_RES_START		(SZ_16M + SZ_2M)
@@ -310,7 +311,9 @@ static void ls2k_bmc_events_fn(struct work_struct *work)
 
 	if (IS_ENABLED(CONFIG_VT)) {
 		/* Re-push the display due to previous PCI-E loss. */
-		set_console(vt_move_to_console(MAX_NR_CONSOLES - 1, 1));
+		console_lock();
+		update_screen(vc_cons[fg_console].d);
+		console_unlock();
 	}
 }
 

-- 
2.49.0

[PATCH RFC 4/5] mfd: ls2kbmc: able to compile as a module

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

Make ls2kmc able to be compiled as a module

Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 763ce6a34782bdd5d2b1a4d840c75b040092d83e..a7a9f97af248c88489dc1203a1ba05f2ce4827df 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2494,7 +2494,7 @@ config MFD_LOONGSON_SE
 	  which will forward them to the corresponding engine.
 
 config MFD_LS2K_BMC_CORE
-	bool "Loongson-2K Board Management Controller Support"
+	tristate "Loongson-2K Board Management Controller Support"
 	depends on PCI && ACPI_GENERIC_GSI
 	select MFD_CORE
 	help

-- 
2.49.0

[PATCH RFC 5/5] mfd: ls2kbmc: capture the reset event of BMC through GPIO

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

The reset event of BMC is captured through GPIO. However, this driver
bypasses the GPIO framework and directly accesses the GPIO controller
through the fixed address. When the same GPIO controller is also
exposed through ACPI and probed by the corresponding GPIO driver,
there would be a conflict between the two drivers.

This patch will try to find the GPIO through declared GPIO pin in the
_CRS resources of the ACPI node. If no such delaration is found, the
driver will fall back to search for the correct GPIO controller and pin
according to the fixed address and pin number. A possible DSDT
declaration for the GPIO pin might be as follows:

    Device (BMC0) {
        Name (_ADR, ...) // Match the PCI address of the BMC device
        // \_SB.GPO1 is the ACPI path of the GPIO controller
        Name (_CRS, ResourceTemplate () {
            GpioInt (Edge, ActiveLow, Exclusive, PullNone, 0,
                     "\\_SB.GPO1", 0) {
                14 // 14 is the GPIO pin number
            }
    }

Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 162 +++++++++++++++++++++++++++++++-------------
 1 file changed, 115 insertions(+), 47 deletions(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index 4ceae6c70fb27ae2d6a2a92f4f45a376f1cdb699..5005908802766cf855bc48a4d7d73495dea16e9c 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -26,6 +26,9 @@
 #include <linux/stop_machine.h>
 #include <linux/vt_kern.h>
 #include <linux/console.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio.h>
 
 /* LS2K BMC resources */
 #define LS2K_DISPLAY_RES_START		(SZ_16M + SZ_2M)
@@ -81,18 +84,6 @@
 
 #define PCI_REG_STRIDE			0x4
 
-#define LS2K_BMC_RESET_GPIO		14
-#define LOONGSON_GPIO_REG_BASE		0x1FE00500
-#define LOONGSON_GPIO_REG_SIZE		0x18
-#define LOONGSON_GPIO_OEN		0x0
-#define LOONGSON_GPIO_FUNC		0x4
-#define LOONGSON_GPIO_INTPOL		0x10
-#define LOONGSON_GPIO_INTEN		0x14
-
-#define LOONGSON_IO_INT_BASE		16
-#define LS2K_BMC_RESET_GPIO_INT_VEC	(LS2K_BMC_RESET_GPIO % 8)
-#define LS2K_BMC_RESET_GPIO_GSI		(LOONGSON_IO_INT_BASE + LS2K_BMC_RESET_GPIO_INT_VEC)
-
 enum {
 	LS2K_BMC_DISPLAY,
 	LS2K_BMC_IPMI0,
@@ -186,6 +177,7 @@ struct ls2k_bmc_ddata {
 	struct work_struct bmc_reset_work;
 	struct ls2k_bmc_pci_data bmc_pci_data;
 	struct ls2k_bmc_bridge_pci_data bridge_pci_data;
+	struct gpio_desc *reset_gpio;
 };
 
 static bool ls2k_bmc_bar0_addr_is_set(struct pci_dev *pdev)
@@ -334,6 +326,22 @@ static irqreturn_t ls2k_bmc_interrupt(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t ls2k_bmc_gpio_interrupt(int irq, void *arg)
+{
+	struct ls2k_bmc_ddata *ddata = arg;
+
+	int val = gpiod_get_raw_value(ddata->reset_gpio);
+
+	/*
+	 * The GPIO is active low, so when the value is 0,
+	 * it indicates a reset event.
+	 */
+	if (val == 0)
+		return ls2k_bmc_interrupt(irq, arg);
+
+	return IRQ_NONE;
+}
+
 /*
  * Saves the BMC parent device (LS7A) and its own PCI configuration space registers
  * that need to be restored after BMC reset.
@@ -375,11 +383,83 @@ static void ls2k_bmc_save_pci_data(struct pci_dev *pdev, struct ls2k_bmc_ddata *
 	pci_read_config_dword(pdev, PCI_INTERRUPT_LINE, &ddata->bmc_pci_data.interrupt_line);
 }
 
+static int ls2k_bmc_gpiochip_find(struct gpio_chip *gc, const void *data)
+{
+	struct acpi_device *adev;
+	struct list_head resource_list;
+	struct resource_entry *rentry;
+	struct fwnode_handle *fwnode = gc->fwnode ?: gc->parent->fwnode;
+	phys_addr_t start_addr = (phys_addr_t) data;
+	int ret, found = 0;
+
+	if (!is_acpi_node(fwnode))
+		goto out;
+
+	adev = to_acpi_device_node(fwnode);
+	if (!adev)
+		goto out;
+
+	INIT_LIST_HEAD(&resource_list);
+
+	ret = acpi_dev_get_memory_resources(adev, &resource_list);
+	if (ret < 0)
+		goto out;
+	rentry = list_first_entry_or_null(&resource_list, struct resource_entry, node);
+	if (!rentry)
+		goto free_resource_list;
+	if (rentry->res->start == start_addr)
+		found = 1;
+
+free_resource_list:
+	acpi_dev_free_resource_list(&resource_list);
+out:
+	return found;
+}
+
+static struct gpio_desc *ls2k_bmc_find_gpio(struct ls2k_bmc_ddata *ddata)
+{
+	/*
+	 * In conventional way, the GPIO should be obtained through ACPI or
+	 * device tree. However, when the information is not available,
+	 * we should find the GPIO according to the convention of the server
+	 * boards with LS2K BMC, the gpio signal relelecting the reset event
+	 * of the BMC should be connected to pin 14 of the GPIO input of
+	 * the first CPU node. The address of that GPIO controller is fixed.
+	 */
+	static const phys_addr_t LOONGSON_GPIO_REG_BASE = 0x1FE00500;
+	static const unsigned int LS2K_BMC_RESET_GPIO = 14;
+	struct gpio_desc *desc;
+	unsigned int legacy_gpio;
+	int ret;
+	struct gpio_device *gdev __free(gpio_device_put) = NULL;
+
+	dev_dbg(ddata->dev, "Searching for GPIO chip at address %pa\n", &LOONGSON_GPIO_REG_BASE);
+
+	gdev = gpio_device_find((void *)LOONGSON_GPIO_REG_BASE, ls2k_bmc_gpiochip_find);
+
+	if (!gdev) {
+		dev_dbg(ddata->dev, "cannot find GPIO chip at address %pa, deferring\n",
+			&LOONGSON_GPIO_REG_BASE);
+		return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	desc = gpio_device_get_desc(gdev, LS2K_BMC_RESET_GPIO);
+	if (IS_ERR(desc))
+		return desc;
+
+	// XXX: might be better to use gpiod_request()
+	legacy_gpio = desc_to_gpio(desc);
+	ret = devm_gpio_request_one(ddata->dev, legacy_gpio, GPIOF_IN, dev_name(ddata->dev));
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	return gpio_to_desc(legacy_gpio);
+}
+
 static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
 {
 	struct pci_dev *pdev = to_pci_dev(ddata->dev);
-	void __iomem *gpio_base;
-	int gpio_irq, ret, val;
+	int gpio_irq, ret;
 
 	ls2k_bmc_save_pci_data(pdev, ddata);
 
@@ -392,44 +472,32 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
 		return ret;
 	}
 
-	gpio_base = ioremap(LOONGSON_GPIO_REG_BASE, LOONGSON_GPIO_REG_SIZE);
-	if (!gpio_base)
-		return -ENOMEM;
-
-	/* Disable GPIO output */
-	val = readl(gpio_base + LOONGSON_GPIO_OEN);
-	writel(val | BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_OEN);
-
-	/* Enable GPIO functionality */
-	val = readl(gpio_base + LOONGSON_GPIO_FUNC);
-	writel(val & ~BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_FUNC);
-
-	/* Set GPIO interrupts to low-level active */
-	val = readl(gpio_base + LOONGSON_GPIO_INTPOL);
-	writel(val & ~BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_INTPOL);
-
-	/* Enable GPIO interrupts */
-	val = readl(gpio_base + LOONGSON_GPIO_INTEN);
-	writel(val | BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_INTEN);
+	ddata->reset_gpio = devm_gpiod_get_index_optional(&pdev->dev, NULL, 0, GPIOD_IN);
+	if (IS_ERR(ddata->reset_gpio)) {
+		ret = PTR_ERR(ddata->reset_gpio);
+		ddata->reset_gpio = NULL;
+		return dev_err_probe(ddata->dev, ret, "Failed to get reset GPIO\n");
+	}
+	if (ddata->reset_gpio == NULL) {
+		ddata->reset_gpio = ls2k_bmc_find_gpio(ddata);
+		if (IS_ERR(ddata->reset_gpio)) {
+			ret = PTR_ERR(ddata->reset_gpio);
+			ddata->reset_gpio = NULL;
+			return dev_err_probe(ddata->dev, ret, "Failed to find reset GPIO\n");
+		}
+	}
 
-	iounmap(gpio_base);
+	gpio_irq = gpiod_to_irq(ddata->reset_gpio);
 
-	/*
-	 * Since gpio_chip->to_irq is not implemented in the Loongson-3 GPIO driver,
-	 * acpi_register_gsi() is used to obtain the GPIO IRQ. The GPIO interrupt is a
-	 * watchdog interrupt that is triggered when the BMC resets.
-	 */
-	gpio_irq = acpi_register_gsi(NULL, LS2K_BMC_RESET_GPIO_GSI, ACPI_EDGE_SENSITIVE,
-				     ACPI_ACTIVE_LOW);
 	if (gpio_irq < 0)
-		return gpio_irq;
+		return dev_err_probe(ddata->dev, gpio_irq, "Failed to get GPIO IRQ\n");
 
-	ret = devm_request_irq(ddata->dev, gpio_irq, ls2k_bmc_interrupt,
-			       IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc gpio", ddata);
-	if (ret)
-		dev_err(ddata->dev, "Failed to request LS2KBMC GPIO IRQ %d.\n", gpio_irq);
+	ret = devm_request_irq(&pdev->dev, gpio_irq, ls2k_bmc_gpio_interrupt,
+			       IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc reset", ddata);
+
+	if (ret != 0)
+		return dev_err_probe(ddata->dev, ret, "Failed to request GPIO IRQ %d.\n", gpio_irq);
 
-	acpi_unregister_gsi(LS2K_BMC_RESET_GPIO_GSI);
 	return ret;
 }
 

-- 
2.49.0