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Message-ID: <20170718141502.GA18857@kroah.com>
Date: Tue, 18 Jul 2017 16:15:03 +0200
From: Greg Kroah-Hartman <greg@...ah.com>
To: Johannes Poehlmann <johannes.poehlmann@...-labs.de>
Cc: linux-kernel@...r.kernel.org, Evgeniy Polyakov <zbr@...emap.net>
Subject: Re: [PATCH v3 1/4] w1: ds1wm: fix and simplify register access
On Tue, Jul 18, 2017 at 01:26:50PM +0200, Johannes Poehlmann wrote:
> o Replace incorrect register offsett calculation by
> direct configuration of bus_shift in mfd-cell.
> Indirect definition of address-shift by resource size
> was unobvious and should have used a binary log.
> o Make endian clean, make HW-endianness configurable.
> o Use ioread*, iowrite* instead of __raw_readb,__raw_writeb
> to also use memory-barriers when accessing HW-registers.
> We do not want reordering to happen here.
Can you format the above to make it a bit more easier to read?
And why do all of this in one single patch? Shouldn't this be multiple
ones?
>
> Signed-off-by: Johannes Poehlmann <johannes.poehlmann@...-labs.de>
> Acked-by: Evgeniy Polyakov <zbr@...emap.net>
> ---
> drivers/w1/masters/ds1wm.c | 84 ++++++++++++++++++++++++++++++++++++++++++----
> include/linux/mfd/ds1wm.h | 9 +++++
> 2 files changed, 87 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c
> index fd2e9da..6bba2fe 100644
> --- a/drivers/w1/masters/ds1wm.c
> +++ b/drivers/w1/masters/ds1wm.c
> @@ -95,7 +95,8 @@ static struct {
>
> struct ds1wm_data {
> void __iomem *map;
> - int bus_shift; /* # of shifts to calc register offsets */
> + unsigned int bus_shift; /* # of shifts to calc register offsets */
> + int is_hw_big_endian;
bool?
> struct platform_device *pdev;
> const struct mfd_cell *cell;
> int irq;
> @@ -115,12 +116,66 @@ struct ds1wm_data {
> static inline void ds1wm_write_register(struct ds1wm_data *ds1wm_data, u32 reg,
> u8 val)
> {
> - __raw_writeb(val, ds1wm_data->map + (reg << ds1wm_data->bus_shift));
> + if (ds1wm_data->is_hw_big_endian) {
> + switch (ds1wm_data->bus_shift) {
> + case 0:
> + iowrite8(val, ds1wm_data->map + (reg << 0));
> + break;
> + case 1:
> + iowrite16be((u16)val, ds1wm_data->map+(reg<<1));
> + break;
> + case 2:
> + iowrite32be((u32)val, ds1wm_data->map+(reg<<2));
> + break;
> + }
> + } else {
> + switch (ds1wm_data->bus_shift) {
> + case 0:
> + iowrite8(val, ds1wm_data->map + (reg << 0));
> + break;
> + case 1:
> + iowrite16((u16) val, ds1wm_data->map+(reg << 1));
> + break;
> + case 2:
> + iowrite32((u32) val, ds1wm_data->map+(reg << 2));
> + break;
> + }
> + }
> }
>
> static inline u8 ds1wm_read_register(struct ds1wm_data *ds1wm_data, u32 reg)
> {
> - return __raw_readb(ds1wm_data->map + (reg << ds1wm_data->bus_shift));
> +
> + u32 val = 0;
> +
> + if (ds1wm_data->is_hw_big_endian) {
> + switch (ds1wm_data->bus_shift) {
> + case 0:
> + val = ioread8(ds1wm_data->map + (reg << 0));
> + break;
> + case 1:
> + val = ioread16be(ds1wm_data->map + (reg << 1));
> + break;
> + case 2:
> + val = ioread32be(ds1wm_data->map + (reg << 2));
> + break;
> + }
> + } else {
> + switch (ds1wm_data->bus_shift) {
> + case 0:
> + val = ioread8(ds1wm_data->map + (reg << 0));
> + break;
> + case 1:
> + val = ioread16(ds1wm_data->map + (reg << 1));
> + break;
> + case 2:
> + val = ioread32(ds1wm_data->map + (reg << 2));
> + break;
> + }
> + }
> + dev_dbg(&ds1wm_data->pdev->dev,
> + "ds1wm_read_register reg: %d, 32 bit val:%x\n", reg, val);
> + return (u8) val;
> }
>
>
> @@ -473,9 +528,6 @@ static int ds1wm_probe(struct platform_device *pdev)
> if (!ds1wm_data->map)
> return -ENOMEM;
>
> - /* calculate bus shift from mem resource */
> - ds1wm_data->bus_shift = resource_size(res) >> 3;
> -
> ds1wm_data->pdev = pdev;
> ds1wm_data->cell = mfd_get_cell(pdev);
> if (!ds1wm_data->cell)
> @@ -484,6 +536,26 @@ static int ds1wm_probe(struct platform_device *pdev)
> if (!plat)
> return -ENODEV;
>
> + /* how many bits to shift register number to get register offset */
> + if (plat->bus_shift > 2) {
> + dev_err(&ds1wm_data->pdev->dev,
> + "illegal bus shift %d, not written",
> + ds1wm_data->bus_shift);
> + return -EINVAL;
> + }
> +
> + ds1wm_data->bus_shift = plat->bus_shift;
> + /* make sure resource has space for 8 registers */
> + if ((8 << ds1wm_data->bus_shift) > resource_size(res)) {
> + dev_err(&ds1wm_data->pdev->dev,
> + "memory resource size %d to small, should be %d\n",
> + (int) resource_size(res),
> + 8 << ds1wm_data->bus_shift);
> + return -EINVAL;
> + }
> +
> + ds1wm_data->is_hw_big_endian = plat->is_hw_big_endian;
> +
> res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> if (!res)
> return -ENXIO;
> diff --git a/include/linux/mfd/ds1wm.h b/include/linux/mfd/ds1wm.h
> index 38a372a..4efd626 100644
> --- a/include/linux/mfd/ds1wm.h
> +++ b/include/linux/mfd/ds1wm.h
> @@ -3,6 +3,7 @@
> struct ds1wm_driver_data {
> int active_high;
> int clock_rate;
> +
> /* in milliseconds, the amount of time to */
> /* sleep following a reset pulse. Zero */
> /* should work if your bus devices recover*/
> @@ -10,4 +11,12 @@ struct ds1wm_driver_data {
> /* ds1wm implements the precise timings of*/
> /* a reset pulse/presence detect sequence.*/
> unsigned int reset_recover_delay;
> +
> + /* Say 1 here for big endian Hardware */
> + /* (only relevant with bus-shift > 0 */
> + int is_hw_big_endian;
bool?
And who is setting this? What is the initial value?
> +
> + /* left shift of register number to get register address offsett */
> + /* only 0,1,2 allowed for 8,16 or 32 bit bus width respectively */
> + unsigned int bus_shift;
u8?
Please use multi-line comments in the correct format, checkpatch.pl
should have complained about these, right?
thanks,
greg k-h
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