linux-kernel - [PATCH v4 3/6] i3c: mipi-i3c-hci: Add a quirk to set PIO mode

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Message-ID: <20240821133554.391937-4-Shyam-sundar.S-k@amd.com>
Date: Wed, 21 Aug 2024 19:05:51 +0530
From: Shyam Sundar S K <Shyam-sundar.S-k@....com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>, Jarkko Nikula
	<jarkko.nikula@...ux.intel.com>
CC: Guruvendra Punugupati <Guruvendra.Punugupati@....com>, Krishnamoorthi M
	<krishnamoorthi.m@....com>, <linux-i3c@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, Shyam Sundar S K <Shyam-sundar.S-k@....com>
Subject: [PATCH v4 3/6] i3c: mipi-i3c-hci: Add a quirk to set PIO mode

The AMD HCI controller currently only supports PIO mode but exposes DMA
rings to the OS, which leads to the controller being configured in DMA
mode. To address this, add a quirk to avoid configuring the controller in
DMA mode and default to PIO mode.

Additionally, introduce a generic quirk infrastructure to the mipi-i3c-hci
driver to facilitate seamless future quirk additions.

Co-developed-by: Krishnamoorthi M <krishnamoorthi.m@....com>
Signed-off-by: Krishnamoorthi M <krishnamoorthi.m@....com>
Co-developed-by: Guruvendra Punugupati <Guruvendra.Punugupati@....com>
Signed-off-by: Guruvendra Punugupati <Guruvendra.Punugupati@....com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>
---
 drivers/i3c/master/mipi-i3c-hci/core.c | 9 ++++++++-
 drivers/i3c/master/mipi-i3c-hci/hci.h  | 1 +
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
index d1952a5619d4..3aa4aa9deb56 100644
--- a/drivers/i3c/master/mipi-i3c-hci/core.c
+++ b/drivers/i3c/master/mipi-i3c-hci/core.c
@@ -754,6 +754,11 @@ static int i3c_hci_init(struct i3c_hci *hci)
 		return -EINVAL;
 	}
 
+	/* Quirk for HCI_QUIRK_PIO_MODE on AMD platforms */
+	regval = reg_read(HCI_VERSION);
+	if (hci->quirks & HCI_QUIRK_PIO_MODE)
+		hci->RHS_regs = NULL;
+
 	/* Try activating DMA operations first */
 	if (hci->RHS_regs) {
 		reg_clear(HC_CONTROL, HC_CONTROL_PIO_MODE);
@@ -804,6 +809,8 @@ static int i3c_hci_probe(struct platform_device *pdev)
 	/* temporary for dev_printk's, to be replaced in i3c_master_register */
 	hci->master.dev.init_name = dev_name(&pdev->dev);
 
+	hci->quirks = (unsigned long)device_get_match_data(&pdev->dev);
+
 	ret = i3c_hci_init(hci);
 	if (ret)
 		return ret;
@@ -836,7 +843,7 @@ static const __maybe_unused struct of_device_id i3c_hci_of_match[] = {
 MODULE_DEVICE_TABLE(of, i3c_hci_of_match);
 
 static const struct acpi_device_id i3c_hci_acpi_match[] = {
-	{"AMDI5017"},
+	{"AMDI5017", HCI_QUIRK_PIO_MODE},
 	{}
 };
 MODULE_DEVICE_TABLE(acpi, i3c_hci_acpi_match);
diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
index f94d95e024be..c56b838fb431 100644
--- a/drivers/i3c/master/mipi-i3c-hci/hci.h
+++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
@@ -135,6 +135,7 @@ struct i3c_hci_dev_data {
 
 /* list of quirks */
 #define HCI_QUIRK_RAW_CCC	BIT(1)	/* CCC framing must be explicit */
+#define HCI_QUIRK_PIO_MODE	BIT(2)  /* Set PIO mode for AMD platforms */
 
 
 /* global functions */
-- 
2.25.1