[PATCH] drm/aspeed: Add sysfs for output settings

[Joel Stanley]

These settings are used by an ASPEED BMC to determine when the host is
trying to drive the display over PCIe (vga_pw) and to switch the
output between PCIe and the internal graphics device (dac_mux).

The valid values for the dac mux are:

 00: VGA mode (default, aka PCIe)
 01: Graphics CRT (aka BMC internal graphics, this driver)
 10: Pass through mode from video input port A
 11: Pass through mode from video input port B

Values for the read-only vga password register are:

 1: Host driving the display
 0: Host not driving the display

Signed-off-by: Joel Stanley <j...@jms.id.au>
---
 drivers/gpu/drm/aspeed/aspeed_gfx_drv.c | 71 +++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c 
b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c
index 903f4f304647..9e06a3683f8a 100644
--- a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c
+++ b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c
@@ -205,6 +205,69 @@ static const struct of_device_id aspeed_gfx_match[] = {
        { }
 };
 
+#define ASPEED_SCU_VGA0                0x50
+#define ASPEED_SCU_MISC_CTRL   0x2c
+
+static ssize_t dac_mux_store(struct device *dev, struct device_attribute *attr,
+                            const char *buf, size_t count)
+{
+       struct aspeed_gfx *priv = dev_get_drvdata(dev);
+       u32 val;
+       int rc;
+
+       rc = kstrtou32(buf, 0, &val);
+       if (rc)
+               return rc;
+
+       if (val < 0 || val > 3)
+               return -EINVAL;
+
+       rc = regmap_update_bits(priv->scu, ASPEED_SCU_MISC_CTRL, 0x30000, val 
<< 16);
+       if (rc < 0)
+               return 0;
+
+       return count;
+}
+
+static ssize_t dac_mux_show(struct device *dev, struct device_attribute *attr, 
char *buf)
+{
+       struct aspeed_gfx *priv = dev_get_drvdata(dev);
+       u32 reg;
+       int rc;
+
+       rc = regmap_read(priv->scu, ASPEED_SCU_MISC_CTRL, &reg);
+       if (rc)
+               return rc;
+
+       return sprintf(buf, "%u\n", (reg >> 16) & 0x3);
+}
+static DEVICE_ATTR_RW(dac_mux);
+
+static ssize_t
+vga_pw_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+       struct aspeed_gfx *priv = dev_get_drvdata(dev);
+       u32 reg;
+       int rc;
+
+       rc = regmap_read(priv->scu, ASPEED_SCU_VGA0, &reg);
+       if (rc)
+               return rc;
+
+       return sprintf(buf, "%u\n", reg & 1);
+}
+static DEVICE_ATTR_RO(vga_pw);
+
+static struct attribute *aspeed_sysfs_entries[] = {
+       &dev_attr_vga_pw.attr,
+       &dev_attr_dac_mux.attr,
+       NULL,
+};
+
+static struct attribute_group aspeed_sysfs_attr_group = {
+       .attrs = aspeed_sysfs_entries,
+};
+
 static int aspeed_gfx_probe(struct platform_device *pdev)
 {
        struct aspeed_gfx *priv;
@@ -219,6 +282,12 @@ static int aspeed_gfx_probe(struct platform_device *pdev)
        if (ret)
                return ret;
 
+       dev_set_drvdata(&pdev->dev, priv);
+
+       ret = sysfs_create_group(&pdev->dev.kobj, &aspeed_sysfs_attr_group);
+       if (ret)
+               return ret;
+
        ret = drm_dev_register(&priv->drm, 0);
        if (ret)
                goto err_unload;
@@ -227,6 +296,7 @@ static int aspeed_gfx_probe(struct platform_device *pdev)
        return 0;
 
 err_unload:
+       sysfs_remove_group(&pdev->dev.kobj, &aspeed_sysfs_attr_group);
        aspeed_gfx_unload(&priv->drm);
 
        return ret;
@@ -236,6 +306,7 @@ static int aspeed_gfx_remove(struct platform_device *pdev)
 {
        struct drm_device *drm = platform_get_drvdata(pdev);
 
+       sysfs_remove_group(&pdev->dev.kobj, &aspeed_sysfs_attr_group);
        drm_dev_unregister(drm);
        aspeed_gfx_unload(drm);
 
-- 
2.28.0

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