Hello.
Atsushi Nemoto wrote:
This is the driver for the Toshiba TX4938 SoC EBUS controller ATA mode.
It has custom set_pio_mode and some hacks for big endian.
Signed-off-by: Atsushi Nemoto <anemo@xxxxxxxxxxxxx>
diff --git a/drivers/ide/mips/tx4938ide.c b/drivers/ide/mips/tx4938ide.c
new file mode 100644
index 0000000..fa660f9
--- /dev/null
+++ b/drivers/ide/mips/tx4938ide.c
@@ -0,0 +1,310 @@
+/*
+ * TX4938 internal IDE driver
+ * Based on tx4939ide.c.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * (C) Copyright TOSHIBA CORPORATION 2005-2007
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/ide.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <asm/txx9/tx4938.h>
+
+static void tx4938ide_tune_ebusc(unsigned int ebus_ch,
+ unsigned int gbus_clock,
+ u8 pio)
+{
+ struct ide_timing *t = ide_timing_find_mode(XFER_PIO_0 + pio);
+ u64 cr = __raw_readq(&tx4938_ebuscptr->cr[ebus_ch]);
+ unsigned int sp = (cr >> 4) & 3;
+ unsigned int clock = gbus_clock / (4 - sp);
+ unsigned int cycle = 1000000000 / clock;
Hm, couldn't all these values be calculated only once?
+ unsigned int wt, shwt;
+
+ /* Minimum DIOx- active time */
+ wt = DIV_ROUND_UP(t->act8b, cycle) - 2;
+ /* IORDY setup time: 35ns */
+ wt = max(wt, DIV_ROUND_UP(35, cycle));
Same comment about calculating only once...
+ /* actual wait-cycle is max(wt & ~1, 1) */
+ if (wt > 2 && (wt & 1))
+ wt++;
+ wt &= ~1;
+ /* Address-valid to DIOR/DIOW setup */
It's really address valid to -CSx assertion and -CSx to -DIOx assertion
setup time, and contrarywise, -DIOx to -CSx release and -CSx release to
address invalid hold time, so it actualy applies 4 times and so constitutes
-DIOx recovery time. It's worth to check if the minimum cycle time is reached
with the setup time -- for PIO mode 0, minimum setup is 70 ns, multiplying
that by 4 gives 280 ns recovery and adding 290 ns active time gives 570 ns
cycle while the minimum is 600 ns. Luckily, PIO0 seems the only problematic
mode as I doubt that EBUS controller can do back-to-back IDE reads/writes
keeping address and/or -CSx asserted in-between amounting to recovery time
being only 2x/3x setup times -- in the worst, 2x case PIO mode 3 would also
have too little cycle/recovery time...
+ shwt = DIV_ROUND_UP(t->setup, cycle);
+
+ pr_debug("tx4938ide: ebus %d, bus cycle %dns, WT %d, SHWT %d\n",
+ ebus_ch, cycle, wt, shwt);
+
+ __raw_writeq((cr & ~(0x3f007ull)) | (wt << 12) | shwt,
+ &tx4938_ebuscptr->cr[ebus_ch]);
Unneeded parens around the numeric constant.
+static int __init tx4938ide_probe(struct platform_device *pdev)
+{
[...]
+ mapbase = (unsigned long)devm_ioremap(&pdev->dev, res->start,
+ res->end - res->start + 1);
Calling devm_ioremap() on the whole 128 KB region wasn't such a great idea
perhaps...
+ ret = ide_host_add(&d, hws, &host);
+ if (ret)
+ return ret;
+ platform_set_drvdata(pdev, host);
+ return 0;
I'd suggest shorter:
if (!ret)
platform_set_drvdata(pdev, host);
return ret;
MBR, Sergei
