linux-kernel - [PATCH 2/7] parport_pc: Let chipset drivers mask unsupported modes

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Message-Id: <20230108215656.6433-2-sudipm.mukherjee@gmail.com>
Date:   Sun,  8 Jan 2023 21:56:51 +0000
From:   Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org,
        "Maciej W. Rozycki" <macro@...am.me.uk>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 2/7] parport_pc: Let chipset drivers mask unsupported modes

From: "Maciej W. Rozycki" <macro@...am.me.uk>

Rename `parport_pc_probe_port' to `__parport_pc_probe_port' and add a
`mode_mask' parameter so that callers can specify a mask of unsupported
modes to exclude even if mode probing seems to indicate otherwise.  Add
a `parport_pc_probe_port' wrapper with an implicit mask of 0 for the
current callers to use.

No functional change at this point, but the configuration of data write
handlers is now no longer intertwined with determination and reporting
of available modes.

Signed-off-by: Maciej W. Rozycki <macro@...am.me.uk>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
---
 drivers/parport/parport_pc.c | 45 ++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
index de7afbea96cd..9daaaaa305e6 100644
--- a/drivers/parport/parport_pc.c
+++ b/drivers/parport/parport_pc.c
@@ -2000,11 +2000,12 @@ static int parport_dma_probe(struct parport *p)
 static LIST_HEAD(ports_list);
 static DEFINE_SPINLOCK(ports_lock);
 
-struct parport *parport_pc_probe_port(unsigned long int base,
-				      unsigned long int base_hi,
-				      int irq, int dma,
-				      struct device *dev,
-				      int irqflags)
+static struct parport *__parport_pc_probe_port(unsigned long int base,
+					       unsigned long int base_hi,
+					       int irq, int dma,
+					       struct device *dev,
+					       int irqflags,
+					       unsigned int mode_mask)
 {
 	struct parport_pc_private *priv;
 	struct parport_operations *ops;
@@ -2116,18 +2117,28 @@ struct parport *parport_pc_probe_port(unsigned long int base,
 	    p->dma != PARPORT_DMA_NOFIFO &&
 	    priv->fifo_depth > 0 && p->irq != PARPORT_IRQ_NONE) {
 		p->modes |= PARPORT_MODE_ECP | PARPORT_MODE_COMPAT;
+		if (p->dma != PARPORT_DMA_NONE)
+			p->modes |= PARPORT_MODE_DMA;
+	} else
+		/* We can't use the DMA channel after all. */
+		p->dma = PARPORT_DMA_NONE;
+#endif /* Allowed to use FIFO/DMA */
+
+	p->modes &= ~mode_mask;
+
+#ifdef CONFIG_PARPORT_PC_FIFO
+	if ((p->modes & PARPORT_MODE_COMPAT) != 0)
 		p->ops->compat_write_data = parport_pc_compat_write_block_pio;
 #ifdef CONFIG_PARPORT_1284
+	if ((p->modes & PARPORT_MODE_ECP) != 0)
 		p->ops->ecp_write_data = parport_pc_ecp_write_block_pio;
-#endif /* IEEE 1284 support */
-		if (p->dma != PARPORT_DMA_NONE) {
+#endif
+	if ((p->modes & (PARPORT_MODE_ECP | PARPORT_MODE_COMPAT)) != 0) {
+		if ((p->modes & PARPORT_MODE_DMA) != 0)
 			pr_cont(", dma %d", p->dma);
-			p->modes |= PARPORT_MODE_DMA;
-		} else
+		else
 			pr_cont(", using FIFO");
-	} else
-		/* We can't use the DMA channel after all. */
-		p->dma = PARPORT_DMA_NONE;
+	}
 #endif /* Allowed to use FIFO/DMA */
 
 	pr_cont(" [");
@@ -2237,6 +2248,16 @@ do {									\
 		platform_device_unregister(pdev);
 	return NULL;
 }
+
+struct parport *parport_pc_probe_port(unsigned long int base,
+				      unsigned long int base_hi,
+				      int irq, int dma,
+				      struct device *dev,
+				      int irqflags)
+{
+	return __parport_pc_probe_port(base, base_hi, irq, dma,
+				       dev, irqflags, 0);
+}
 EXPORT_SYMBOL(parport_pc_probe_port);
 
 void parport_pc_unregister_port(struct parport *p)
-- 
2.30.2