On Thu, 15 May 2025, Binbin Zhou wrote:
> Since the display is a sub-function of the Loongson-2K BMC, when the
> BMC reset, the entire BMC PCIe is disconnected, including the display
> which is interrupted.
>
> Not only do you need to save/restore the relevant PCIe registers
> throughout the reset process, but you also need to re-push the display
> to the monitor at the end.
>
> Co-developed-by: Chong Qiao <qiaoch...@loongson.cn>
> Signed-off-by: Chong Qiao <qiaoch...@loongson.cn>
> Signed-off-by: Binbin Zhou <zhoubin...@loongson.cn>
> ---
> drivers/mfd/ls2kbmc-mfd.c | 242 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 242 insertions(+)
>
> diff --git a/drivers/mfd/ls2kbmc-mfd.c b/drivers/mfd/ls2kbmc-mfd.c
> index b309f6132c24..4d35a13b3da5 100644
> --- a/drivers/mfd/ls2kbmc-mfd.c
> +++ b/drivers/mfd/ls2kbmc-mfd.c
> @@ -9,8 +9,11 @@
> */
>
> #include <linux/aperture.h>
> +#include <linux/delay.h>
> #include <linux/errno.h>
> #include <linux/init.h>
> +#include <linux/iopoll.h>
> +#include <linux/kbd_kern.h>
> #include <linux/kernel.h>
> #include <linux/mfd/core.h>
> #include <linux/module.h>
> @@ -18,6 +21,8 @@
> #include <linux/pci_ids.h>
> #include <linux/platform_data/simplefb.h>
> #include <linux/platform_device.h>
> +#include <linux/stop_machine.h>
> +#include <linux/vt_kern.h>
>
> #define LS2K_DISPLAY_RES_START (SZ_16M + SZ_2M)
> #define LS2K_IPMI_RES_SIZE 0x1c
> @@ -27,6 +32,9 @@
> #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)
>
> +#define LS2K_BMC_RESET_DELAY (60 * HZ)
> +#define LS2K_BMC_RESET_WAIT (10 * HZ)
> +
> static struct resource ls2k_display_resources[] = {
> DEFINE_RES_MEM_NAMED(LS2K_DISPLAY_RES_START, SZ_4M, "simpledrm-res"),
> };
> @@ -60,6 +68,227 @@ static struct mfd_cell ls2k_bmc_cells[] = {
> MFD_CELL_RES("ls2k-ipmi-si", ls2k_ipmi4_resources),
> };
>
> +static const u32 index[] = { 0x4, 0x10, 0x14, 0x18, 0x1c, 0x20, 0x24,
> + 0x30, 0x3c, 0x54, 0x58, 0x78, 0x7c, 0x80 };
> +static const u32 cindex[] = { 0x4, 0x10, 0x3c };
What are these? You need to define them or at least provide a comment
that describes what they are and how they're used.
> +struct ls2k_bmc_pci_data {
> + u32 d80c;
> + u32 d71c;
> + u32 data[14];
> + u32 cdata[3];
To the uninitiated, this is all gibberish.
Either change the nomenclature or provide commentary.
> +};
> +
> +struct ls2k_bmc_pdata {
> + struct device *dev;
> + struct work_struct reset_work;
> + unsigned long reset_time;
This always appears to be jiffies - is it used elsewhere?
> + struct ls2k_bmc_pci_data pci_data;
> +};
> +
> +static bool ls2k_bmc_bar0_addr_is_set(struct pci_dev *ppdev)
> +{
> + u32 addr;
> +
> + pci_read_config_dword(ppdev, PCI_BASE_ADDRESS_0, &addr);
> + addr &= PCI_BASE_ADDRESS_MEM_MASK;
> +
> + return addr ? true : false;
> +}
> +
> +static bool ls2k_bmc_check_pcie_connected(struct pci_dev *parent,
> + struct ls2k_bmc_pdata *priv)
> +{
> + void __iomem *mmio;
> + int sts, ret;
> +
> + mmio = pci_iomap(parent, 0, 0x100);
Why 0x100? This should be defined.
> + if (!mmio)
> + return false;
> +
> + writel(readl(mmio) | 0x8, mmio);
> +
> + ret = readl_poll_timeout_atomic(mmio + 0xc, sts, (sts & 0x11) == 0x11,
> + 1000, 1000000);
> + if (ret) {
All of the magic numbers in this function should be defined.
> + pci_iounmap(parent, mmio);
> + dev_err(priv->dev, "PCIE train failed status=0x%x\n", sts);
> + return false;
> + }
> +
> + pci_iounmap(parent, mmio);
> + return true;
> +}
> +
> +static int ls2k_bmc_recover_pci_data(void *data)
> +{
> + struct ls2k_bmc_pdata *priv = data;
> + struct pci_dev *pdev = to_pci_dev(priv->dev);
> + struct pci_dev *parent = pdev->bus->self;
> + bool ready, dirty;
> + u32 i;
> +
> + pci_write_config_dword(parent, PCI_BASE_ADDRESS_2, 0);
> + pci_write_config_dword(parent, PCI_BASE_ADDRESS_3, 0);
> + pci_write_config_dword(parent, PCI_BASE_ADDRESS_4, 0);
You need to provide commentary throughout this driver!
> +
> + for (i = 2000; i > 0 ; i--) {
Why 2000? Please define and explain it.
> + dirty = ls2k_bmc_bar0_addr_is_set(parent);
Since these are bools, you can put the function in an if() statement.
> + if (!dirty)
> + break;
> + mdelay(1);
Why? What are we waiting for?
> + };
> +
> + if (i == 0)
> + dev_warn(priv->dev, "The PCI Bar is not cleared.\n");
But it's okay to continue? Why?
> + for (i = 0; i < ARRAY_SIZE(index); i++)
> + pci_write_config_dword(parent, index[i],
> priv->pci_data.data[i]);
> +
> + pci_write_config_dword(parent, 0x80c, priv->pci_data.d80c);
> + pci_write_config_dword(parent, 0x71c, priv->pci_data.d71c);
> +
> + /* Check if the pcie is connected */
PCI-E
> + ready = ls2k_bmc_check_pcie_connected(parent, priv);
As above.
> + if (!ready)
> + return ready;
> +
> + dev_dbg(priv->dev, "The PCIE recovered done.\n");
How useful is this once development is complete?
> + /* Waiting for u-boot ddr config ready */
Will it always be U-Boot?
Should be "U-Boot" and "DDR".
> + mdelay(jiffies_to_msecs(LS2K_BMC_RESET_WAIT));
Why not define the value in ms already?
> + ready = ls2k_bmc_bar0_addr_is_set(parent);
As above.
> + if (!ready)
> + return ready;
> +
> + for (i = 0; i < ARRAY_SIZE(cindex); i++)
> + pci_write_config_dword(pdev, cindex[i],
> priv->pci_data.cdata[i]);
> +
> + return 0;
> +}
> +
> +static void ls2k_bmc_events_fn(struct work_struct *work)
> +{
> + struct ls2k_bmc_pdata *priv = container_of(work, struct ls2k_bmc_pdata,
> reset_work);
> +
> + /*
> + * The pcie is lost when the BMC resets,
Strange line-breaks. Pick a limit (80-100, etc) and stick to it.
> + * at which point access to the pcie from other CPUs
> + * is suspended to prevent a crash.
> + */
> + stop_machine(ls2k_bmc_recover_pci_data, priv, NULL);
> +
> +#ifdef CONFIG_VT
No avoidable #ifery in C-files please.
> + /* Re-push the display due to previous pcie loss. */
> + set_console(vt_move_to_console(MAX_NR_CONSOLES - 1, 1));
> +#endif
> +
> + dev_info(priv->dev, "Loongson-2K BMC recovered done.\n");
Remove this line - we want clean bootlogs.
> +}
> +
> +static irqreturn_t ls2k_bmc_interrupt(int irq, void *arg)
> +{
> + struct ls2k_bmc_pdata *priv = arg;
> +
> + if (system_state != SYSTEM_RUNNING)
> + return IRQ_HANDLED;
> +
> + /* Skip interrupt in LS2K_BMC_RESET_DELAY */
> + if (time_after(jiffies, priv->reset_time + LS2K_BMC_RESET_DELAY))
> + schedule_work(&priv->reset_work);
> +
> + priv->reset_time = jiffies;
> +
> + return IRQ_HANDLED;
> +}
> +
> +#define 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
Put these up with the reset of the defines.
> +/* The gpio interrupt is a watchdog interrupt that is triggered when the BMC
> resets. */
> +static int ls2k_bmc_gpio_reset_handler(struct ls2k_bmc_pdata *priv)
Why are we now doing GPIO things in here? Why not a GPIO driver?
> +{
> + int gsi = 16 + (BMC_RESET_GPIO & 7);
> + void __iomem *gpio_base;
> + int irq, ret = 0;
> +
> + /* Since Loongson-3A hardware does not support GPIO interrupt cascade,
> + * chip->gpio_to_irq() cannot be implemented,
> + * here acpi_register_gsi() is used to get gpio irq.
> + */
Use proper multi-line commentary as per the Coding Style documentation.
> + irq = acpi_register_gsi(NULL, gsi, ACPI_EDGE_SENSITIVE,
> ACPI_ACTIVE_LOW);
> + if (irq < 0)
> + return irq;
> +
> + gpio_base = ioremap(LOONGSON_GPIO_REG_BASE, LOONGSON_GPIO_REG_SIZE);
> + if (!gpio_base) {
> + ret = PTR_ERR(gpio_base);
> + goto acpi_failed;
> + }
> +
> + writel(readl(gpio_base + LOONGSON_GPIO_OEN) | BIT(BMC_RESET_GPIO),
> + gpio_base + LOONGSON_GPIO_OEN);
> + writel(readl(gpio_base + LOONGSON_GPIO_FUNC) & ~BIT(BMC_RESET_GPIO),
> + gpio_base + LOONGSON_GPIO_FUNC);
> + writel(readl(gpio_base + LOONGSON_GPIO_INTPOL) & ~BIT(BMC_RESET_GPIO),
> + gpio_base + LOONGSON_GPIO_INTPOL);
> + writel(readl(gpio_base + LOONGSON_GPIO_INTEN) | BIT(BMC_RESET_GPIO),
> + gpio_base + LOONGSON_GPIO_INTEN);
> +
> + ret = devm_request_irq(priv->dev, irq, ls2k_bmc_interrupt,
> + IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc
> gpio", priv);
> + if (ret)
> + dev_err(priv->dev, "ls2kbmc gpio request_irq(%d) failed\n",
> irq);
"LS2KBMC" and "GPIO", etc.
> +
> + iounmap(gpio_base);
> +
> +acpi_failed:
> + acpi_unregister_gsi(gsi);
> +
> + return ret;
> +}
> +
> +static void ls2k_bmc_save_pci_data(struct pci_dev *pdev, struct
> ls2k_bmc_pdata *priv)
> +{
> + struct pci_dev *parent = pdev->bus->self;
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(index); i++)
> + pci_read_config_dword(parent, index[i],
> &priv->pci_data.data[i]);
> +
> + for (i = 0; i < ARRAY_SIZE(cindex); i++)
> + pci_read_config_dword(pdev, cindex[i],
> &priv->pci_data.cdata[i]);
> +
> + pci_read_config_dword(parent, 0x80c, &priv->pci_data.d80c);
> + priv->pci_data.d80c = (priv->pci_data.d80c & ~(3 << 17)) | BIT(17);
> +
> + pci_read_config_dword(parent, 0x71c, &priv->pci_data.d71c);
> + priv->pci_data.d71c |= BIT(26);
No magic numbers please. Define them all.
> +}
> +
> +static int ls2k_bmc_pdata_initial(struct pci_dev *pdev, struct
> ls2k_bmc_pdata *priv)
> +{
> + int ret;
> +
> + ls2k_bmc_save_pci_data(pdev, priv);
> +
> + INIT_WORK(&priv->reset_work, ls2k_bmc_events_fn);
> +
> + ret = devm_request_irq(&pdev->dev, pdev->irq, ls2k_bmc_interrupt,
> + IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc
> pcie", priv);
> + if (ret) {
> + dev_err(priv->dev, "ls2kbmc pcie request_irq(%d) failed\n",
> pdev->irq);
> + return ret;
> + }
> +
> + return ls2k_bmc_gpio_reset_handler(priv);
> +}
> +
> /*
> * Currently the Loongson-2K0500 BMC hardware does not have an i2c interface
> to
> * adapt to the resolution.
> @@ -101,12 +330,25 @@ static int ls2k_bmc_probe(struct pci_dev *dev, const
> struct pci_device_id *id)
> {
> int ret = 0;
> resource_size_t base;
> + struct ls2k_bmc_pdata *priv;
> struct simplefb_platform_data pd;
>
> ret = pci_enable_device(dev);
> if (ret)
> return ret;
>
> + priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
> + if (IS_ERR(priv)) {
> + ret = -ENOMEM;
> + goto disable_pci;
> + }
> +
> + priv->dev = &dev->dev;
> +
> + ret = ls2k_bmc_pdata_initial(dev, priv);
> + if (ret)
> + goto disable_pci;
> +
> ret = ls2k_bmc_get_video_mode(dev, &pd);
> if (ret)
> goto disable_pci;
> --
> 2.47.1
>
--
Lee Jones [李琼斯]
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