Re: [PATCH] ide/macide: Convert Mac IDE driver to platform driver

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On Wed, 9 Sep 2020, Geert Uytterhoeven wrote:


Thanks for your patch!


Thanks for your review.

--- a/arch/m68k/mac/config.c +++ b/arch/m68k/mac/config.c

@@ -940,6 +941,50 @@ static const struct resource mac_scsi_ccl_rsrc[] __initconst = {
        },
 };

+static const struct resource mac_ide_quadra_rsrc[] __initconst = {
+       {
+               .flags = IORESOURCE_MEM,
+               .start = 0x50F1A000,
+               .end   = 0x50F1A103,
+       }, {
+               .flags = IORESOURCE_IRQ,
+               .start = IRQ_NUBUS_F,
+               .end   = IRQ_NUBUS_F,
+       },
+};
+
+static const struct resource mac_ide_pb_rsrc[] __initconst = {
+       {
+               .flags = IORESOURCE_MEM,
+               .start = 0x50F1A000,
+               .end   = 0x50F1A103,
+       }, {
+               .flags = IORESOURCE_IRQ,
+               .start = IRQ_NUBUS_C,
+               .end   = IRQ_NUBUS_C,
+       },
+};

As the above two variants are almost identical, perhaps it makes sense 
to drop one of them, drop the const, and override the irq values 
dynamically?


I prefer a declarative or data-driven style, even if it takes a few more 
lines of code. But there is a compromise:

static const struct resource mac_ide_quadra_rsrc[] __initconst = {
	DEFINE_RES_MEM(0x50F1A000, 0x104),
	DEFINE_RES_IRQ(IRQ_NUBUS_F),
}

static const struct resource mac_ide_pb_rsrc[] __initconst = {
	DEFINE_RES_MEM(0x50F1A000, 0x104),
	DEFINE_RES_IRQ(IRQ_NUBUS_C),
}

The reason I didn't use these macros was to avoid making the reader go and 
look up their definitions. Anyway, would that style be preferred here?

I could do the same with the mac_ide_baboon_rsrc[] initializer:

static const struct resource mac_pata_baboon_rsrc[] __initconst = {
        DEFINE_RES_MEM(0x50F1A000, 0x38),
        DEFINE_RES_MEM(0x50F1A038, 0x04),
        DEFINE_RES_IRQ(IRQ_BABOON_1),
};

... but that would lose the IORESOURCE_IRQ_SHAREABLE flag. I'm not sure 
whether that matters (it's a vestige of macide.c).

+
+static const struct resource mac_pata_baboon_rsrc[] __initconst = {
+       {
+               .flags = IORESOURCE_MEM,
+               .start = 0x50F1A000,
+               .end   = 0x50F1A037,
+       }, {
+               .flags = IORESOURCE_MEM,
+               .start = 0x50F1A038,
+               .end   = 0x50F1A03B,
+       }, {
+               .flags = IORESOURCE_IRQ | IORESOURCE_IRQ_SHAREABLE,
+               .start = IRQ_BABOON_1,
+               .end   = IRQ_BABOON_1,
+       },
+};
+
+static const struct pata_platform_info mac_pata_baboon_data __initconst = {
+       .ioport_shift  = 2,
+};

Just wondering: how is this implemented in drivers/ide/macide.c, which
doesn't use the platform info?


That factor of 4 is embedded in the address caclulation:

        for (i = 0; i < 8; i++)
                hw->io_ports_array[i] = base + i * 4;

--- a/drivers/ide/macide.c
+++ b/drivers/ide/macide.c
@@ -18,10 +18,11 @@
 #include <linux/delay.h>
 #include <linux/ide.h>
 #include <linux/module.h>
+#include <linux/platform_device.h>

 #include <asm/macintosh.h>
-#include <asm/macints.h>
-#include <asm/mac_baboon.h>
+
+#define DRV_NAME "mac_ide"

 #define IDE_BASE 0x50F1A000    /* Base address of IDE controller */

Do you still need this definition?
Yes, because it's still used to access IDE_IFR.
Ideally, that should be converted to use the base from the resource,
too.


Yes, that was my thought too. I can make the change if you like, but I 
can't test it until I set up the appropriate hardware (MAC_IDE_QUADRA or 
MAC_IDE_PB). I do own that hardware but it is located in Melbourne and it 
is now illegal to visit Melbourne without official papers. Besides, once I 
can test on that hardware I can replace the entire driver anyway, and 
this kind of refactoring would become moot.


@@ -109,42 +110,65 @@ static const char *mac_ide_name[] =
  * Probe for a Macintosh IDE interface
  */

-static int __init macide_init(void)
+static int mac_ide_probe(struct platform_device *pdev)
 {
-       unsigned long base;
-       int irq;
+       struct resource *mem, *irq;
        struct ide_hw hw, *hws[] = { &hw };
        struct ide_port_info d = macide_port_info;
+       struct ide_host *host;
+       int rc;

        if (!MACH_IS_MAC)
                return -ENODEV;

-       switch (macintosh_config->ide_type) {
-       case MAC_IDE_QUADRA:
-               base = IDE_BASE;
-               irq = IRQ_NUBUS_F;
-               break;
-       case MAC_IDE_PB:
-               base = IDE_BASE;
-               irq = IRQ_NUBUS_C;
-               break;
-       case MAC_IDE_BABOON:
-               base = BABOON_BASE;
-               d.port_ops = NULL;

How does the driver know not to use the special port_ops after
this change?


The driver always uses the special port_ops after this change because it 
no longer handles the MAC_IDE_BABOON case. That case is handled by either 
drivers/ata/pata_platform.c or drivers/ide/ide_platform.c, depending on 
.config.

-               irq = IRQ_BABOON_1;
-               break;
-       default:
+       mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       if (!mem)
+               return -ENODEV;
+
+       irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+       if (!irq)
                return -ENODEV;
+
+       if (!devm_request_mem_region(&pdev->dev, mem->start,
+                                    resource_size(mem), DRV_NAME)) {
+               dev_err(&pdev->dev, "resources busy\n");
+               return -EBUSY;
        }

        printk(KERN_INFO "ide: Macintosh %s IDE controller\n",
                         mac_ide_name[macintosh_config->ide_type - 1]);

-       macide_setup_ports(&hw, base, irq);
+       macide_setup_ports(&hw, mem->start, irq->start);
+
+       rc = ide_host_add(&d, hws, 1, &host);
+       if (rc)
+               goto release_mem;
+
+       platform_set_drvdata(pdev, host);

In general, it's safer to move the platform_set_drvdata() call before
the ide_host_add() call, as the IDE core may start calling into your
driver as soon as the host has been added.  Fortunately you're using
dev_get_drvdata() in the .remove() callback only, and not in other parts
of the driver.


Right.

+       return 0;
+
+release_mem:
+       release_mem_region(mem->start, resource_size(mem));

Not needed, as you used devm_*() for allocation.


OK, I'll remove this. I put it there after I looked at falconide.c and 
wondered whether the automatic release would take place after both init 
failure and exit (or just exit). I see now that pata_gayle.c does it 
differently.

+       return rc;
+}
+
+static int mac_ide_remove(struct platform_device *pdev)
+{
+       struct ide_host *host = dev_get_drvdata(&pdev->dev);

-       return ide_host_add(&d, hws, 1, NULL);
+       ide_host_remove(host);
+       return 0;
 }


Gr{oetje,eeting}s,

                        Geert




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