RE: [PATCH V7 1/7] spi: Add stacked and parallel memories support in SPI core

["Mahapatra, Amit Kumar" <amit.kumar-mahapatra@xxxxxxx>]

Hello Stefan,

> -----Original Message-----
> From: Stefan Binding <sbinding@xxxxxxxxxxxxxxxxxxxxx>
> Sent: Wednesday, April 12, 2023 8:33 PM
> To: Mahapatra, Amit Kumar <amit.kumar-mahapatra@xxxxxxx>;
> broonie@xxxxxxxxxx; tudor.ambarus@xxxxxxxxxx; pratyush@xxxxxxxxxx;
> michael@xxxxxxxx; miquel.raynal@xxxxxxxxxxx; richard@xxxxxx;
> vigneshr@xxxxxx
> Cc: git (AMD-Xilinx) <git@xxxxxxx>; linux-spi@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx;
> nicolas.ferre@xxxxxxxxxxxxx; alexandre.belloni@xxxxxxxxxxx;
> claudiu.beznea@xxxxxxxxxxxxx; Simek, Michal <michal.simek@xxxxxxx>;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; amitrkcian2002@xxxxxxxxx;
> patches@xxxxxxxxxxxxxxxxxxxxx; vitalyr@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH V7 1/7] spi: Add stacked and parallel memories support
> in SPI core
> 
> Hi,
> 
> On 11/04/2023 10:07, Mahapatra, Amit Kumar wrote:
> > Hello Stefan,
> >
> >> -----Original Message-----
> >> From: Stefan Binding <sbinding@xxxxxxxxxxxxxxxxxxxxx>
> >> Sent: Thursday, April 6, 2023 7:14 PM
> >> To: Mahapatra, Amit Kumar <amit.kumar-mahapatra@xxxxxxx>;
> >> broonie@xxxxxxxxxx; tudor.ambarus@xxxxxxxxxx; pratyush@xxxxxxxxxx;
> >> michael@xxxxxxxx; miquel.raynal@xxxxxxxxxxx; richard@xxxxxx;
> >> vigneshr@xxxxxx
> >> Cc: git (AMD-Xilinx) <git@xxxxxxx>; linux-spi@xxxxxxxxxxxxxxx; linux-
> >> kernel@xxxxxxxxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx;
> >> nicolas.ferre@xxxxxxxxxxxxx; alexandre.belloni@xxxxxxxxxxx;
> >> claudiu.beznea@xxxxxxxxxxxxx; Simek, Michal
> <michal.simek@xxxxxxx>;
> >> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; amitrkcian2002@xxxxxxxxx;
> >> patches@xxxxxxxxxxxxxxxxxxxxx; vitalyr@xxxxxxxxxxxxxxxxxxxxx
> >> Subject: RE: [PATCH V7 1/7] spi: Add stacked and parallel memories
> >> support in SPI core
> >>
> >> Hi,
> >>
> >>> -----Original Message-----
> >>> From: Amit Kumar Mahapatra <amit.kumar-mahapatra@xxxxxxx>
> >>> Sent: Thursday, April 6, 2023 7:54 AM
> >>> To: broonie@xxxxxxxxxx; tudor.ambarus@xxxxxxxxxx;
> >>> pratyush@xxxxxxxxxx; michael@xxxxxxxx; miquel.raynal@xxxxxxxxxxx;
> >>> richard@xxxxxx; vigneshr@xxxxxx
> >>> Cc: git@xxxxxxx; sbinding@xxxxxxxxxxxxxxxxxxxxx; linux-
> >>> spi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
> >>> mtd@xxxxxxxxxxxxxxxxxxx; nicolas.ferre@xxxxxxxxxxxxx;
> >>> alexandre.belloni@xxxxxxxxxxx; claudiu.beznea@xxxxxxxxxxxxx;
> >>> michal.simek@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> >>> amitrkcian2002@xxxxxxxxx; Amit Kumar Mahapatra <amit.kumar-
> >>> mahapatra@xxxxxxx>
> >>> Subject: [PATCH V7 1/7] spi: Add stacked and parallel memories
> >> support
> >>> in SPI core
> >>>
> >>> For supporting multiple CS the SPI device need to be aware of all
> >> the CS
> >>> values. So, the "chip_select" member in the spi_device structure is
> >> now
> >>> an
> >>> array that holds all the CS values.
> >>>
> >>> spi_device structure now has a "cs_index_mask" member. This acts as
> >> an
> >>> index to the chip_select array. If nth bit of spi->cs_index_mask is
> >> set
> >>> then the driver would assert spi->chip_select[n].
> >>>
> >>> In parallel mode all the chip selects are asserted/de-asserted
> >>> simultaneously and each byte of data is stored in both devices, the
> >> even
> >>> bits in one, the odd bits in the other. The split is automatically
> >> handled
> >>> by the GQSPI controller. The GQSPI controller supports a maximum of
> >>> two flashes connected in parallel mode. A SPI_CONTROLLER_MULTI_CS
> >>> flag bit is added in the spi controntroller flags, through
> >>> ctlr->flags the spi
> >> core
> >>> will make sure that the controller is capable of handling multiple
> >> chip
> >>> selects at once.
> >>>
> >>> For supporting multiple CS via GPIO the cs_gpiod member of the
> >>> spi_device structure is now an array that holds the gpio descriptor
> >>> for each chipselect.
> >>>
> >>> Multi CS support using GPIO is not tested due to unavailability of
> >>> necessary hardware setup.
> >>>
> >>> Multi CS configuration with one native CS and one GPIO CS is not
> >>> supported as this configuration could not be tested due to
> >>> unavailability of necessary hardware setup.
> >> I've tested this chain on a released laptop (HP EliteBook 840 G9)
> >> which uses SPI to interface to 2 amps, one amp uses a native CS and
> >> the other uses a GPIO CS, and I noticed that when using this chain,
> >> the second amp no longer works.
> > Thank you for testing this patch series on GPIO CS setup. As I don't
> > have a GPIO CS setup, is it possible for you debug the failure and
> > share more details/logs where the problem is?
> >
> > Regards,
> > Amit
> 
> We are willing and able to debug this failure and share the failure logs.
> The first issue that I see is a kernel crash when trying to set the GPIO CS:
> 
> [    2.951658] general protection fault, probably for non-canonical address
> 0xdead000000000122: 0000 [#1] PREEMPT SMP NOPTI [    2.951771] CPU: 9
> PID: 379 Comm: systemd-udevd Tainted: G A           6.3.0-rc3+ #30
> [    2.951826] Hardware name: HP /896D, BIOS U70 Ver. 89.33.02 10/29/2021
> [    2.951882] RIP: 0010:gpiod_set_value_cansleep+0x21/0xa0
> [    2.951941] Code: 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 48 85 ff
> 74 3e 55 48 89 e5 41 55 41 89 f5 41 54 49 89 fc 48 81 ff 00 f0 ff ff 77 2c <48>
> 8b 3f 48 85 ff 74 53 48 83 bf 68 03 00 00 00 74 34 44 89 ee 4c [    2.952043]
> RSP: 0018:ffffc008c0deb928 EFLAGS: 00010287 [    2.952080] RAX:
> 0000000000000001 RBX: ffffa0a489534c00 RCX:
> 0000000000000000
> [    2.952124] RDX: dead000000000122 RSI: 0000000000000001 RDI:
> dead000000000122
> [    2.952167] RBP: ffffc008c0deb938 R08: 0000000000000000 R09:
> ffffc008c0deb868
> [    2.952211] R10: ffffffffffffffff R11: 00000000000000b0 R12:
> dead000000000122
> [    2.952256] R13: 0000000000000001 R14: 0000000000000000 R15:
> 0000000000000000
> [    2.952299] FS:  00007f7fa5b5b880(0000) GS:ffffa0a81f840000(0000)
> knlGS:0000000000000000
> [    2.952369] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    2.952407] CR2: 000055d648427100 CR3: 000000010e960003 CR4:
> 0000000000770ee0
> [    2.952451] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [    2.952492] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7:
> 0000000000000400
> [    2.952533] PKRU: 55555554
> [    2.952561] Call Trace:
> [    2.952579]  <TASK>
> [    2.952598]  spi_set_cs+0x257/0x4a0
> [    2.952630]  spi_setup+0x1a2/0x500
> [    2.952667]  __spi_add_device+0x88/0x160
> [    2.952710]  spi_add_device+0x60/0x90
> [    2.952738]  smi_spi_probe+0x178/0x370 [serial_multi_instantiate]
> [    2.952792]  smi_probe+0xcf/0x110 [serial_multi_instantiate]
> [    2.952854]  platform_probe+0x42/0xb0
> [    2.952885]  really_probe+0x1b2/0x420
> [    2.952914]  __driver_probe_device+0x7e/0x180
> [    2.952947]  driver_probe_device+0x23/0xa0
> [    2.952993]  __driver_attach+0xe4/0x1e0 [    2.953021]  ?
> __pfx___driver_attach+0x10/0x10
> [    2.953061]  bus_for_each_dev+0x7a/0xd0
> [    2.953088]  driver_attach+0x1e/0x30
> [    2.953123]  bus_add_driver+0x11c/0x220
> [    2.953150]  driver_register+0x64/0x130 [    2.953174]  ?
> __pfx_init_module+0x10/0x10 [serial_multi_instantiate]
> [    2.953221]  __platform_driver_register+0x1e/0x30
> [    2.953251]  smi_driver_init+0x1c/0xff0 [serial_multi_instantiate]
> [    2.953310]  do_one_initcall+0x46/0x220 [    2.953339]  ?
> kmalloc_trace+0x2a/0xa0 [    2.953375]  do_init_module+0x52/0x220
> [    2.953411]  load_module+0x223c/0x2460
> [    2.953450]  __do_sys_finit_module+0xc8/0x140 [    2.953479]  ?
> __do_sys_finit_module+0xc8/0x140
> [    2.953510]  __x64_sys_finit_module+0x18/0x20
> [    2.953538]  do_syscall_64+0x38/0x90
> [    2.953574]  entry_SYSCALL_64_after_hwframe+0x72/0xdc
> [    2.953606] RIP: 0033:0x7f7fa5d7476d
> [    2.953639] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa
> 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f
> 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f3 36 0d 00 f7 d8 64 89 01 48
> [    2.953739] RSP: 002b:00007fff1f8dd3b8 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000139
> [    2.956833] RAX: ffffffffffffffda RBX: 000055d648654ab0 RCX:
> 00007f7fa5d7476d
> [    2.959202] RDX: 0000000000000000 RSI: 00007f7fa5c54ded RDI:
> 0000000000000006
> [    2.961542] RBP: 0000000000020000 R08: 0000000000000000 R09:
> 0000000000000000
> [    2.964312] R10: 0000000000000006 R11: 0000000000000246 R12:
> 00007f7fa5c54ded
> [    2.966694] R13: 0000000000000000 R14: 000055d6483f41a0 R15:
> 000055d648654ab0
> [    2.967668] resource: resource sanity check: requesting [mem
> 0x00000000fedc0000-0x00000000fedcffff], which spans more than pnp 00:04
> [mem 0xfedc0000-0xfedc7fff] [    2.968998]  </TASK> [    2.971615] caller
> igen6_probe+0x178/0x8e0 [igen6_edac] mapping multiple BARs [    2.975014]
> Modules linked in: igen6_edac(+) fjes(-)
> serial_multi_instantiate(+) int3403_thermal sch_fq_codel
> int340x_thermal_zone int3400_thermal intel_hid acpi_thermal_rel acpi_tad
> sparse_keymap acpi_pad mac_hid msr parport_pc ppdev lp parport drm
> ramoops reed_solomon efi_pstore ip_tables x_tables autofs4
> spi_pxa2xx_platform dw_dmac dw_dmac_core nvme intel_lpss_pci
> intel_lpss crc32_pclmul thunderbolt i2c_i801 xhci_pci idma64 nvme_core
> i2c_smbus virt_dma xhci_pci_renesas video wmi pinctrl_tigerlake
> [    2.987901] ---[ end trace 0000000000000000 ]--- [    3.157030] RIP:
> 0010:gpiod_set_value_cansleep+0x21/0xa0
> [    3.159077] Code: 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 48 85 ff
> 74 3e 55 48 89 e5 41 55 41 89 f5 41 54 49 89 fc 48 81 ff 00 f0 ff ff 77 2c <48>
> 8b 3f 48 85 ff 74 53 48 83 bf 68 03 00 00 00 74 34 44 89 ee 4c [    3.161461]
> RSP: 0018:ffffc008c0deb928 EFLAGS: 00010287 [    3.164005] RAX:
> 0000000000000001 RBX: ffffa0a489534c00 RCX:
> 0000000000000000
> [    3.166354] RDX: dead000000000122 RSI: 0000000000000001 RDI:
> dead000000000122
> [    3.168499] RBP: ffffc008c0deb938 R08: 0000000000000000 R09:
> ffffc008c0deb868
> [    3.170609] R10: ffffffffffffffff R11: 00000000000000b0 R12:
> dead000000000122
> [    3.172893] R13: 0000000000000001 R14: 0000000000000000 R15:
> 0000000000000000
> [    3.175335] FS:  00007f7fa5b5b880(0000) GS:ffffa0a81f840000(0000)
> knlGS:0000000000000000
> [    3.180434] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    3.183356] CR2: 000055d648427100 CR3: 000000010e960003 CR4:
> 0000000000770ee0
> [    3.185107] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [    3.186840] DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7:
> 0000000000000400
> [    3.188647] PKRU: 55555554

Thank you for sharing the logs.
As per our analysis the spi->cs_gpiod[0] is getting messed up while 
setting it in __spi_add_device( ).
Is it possible for you to do the following changes on top of this patch 
series & re-run your test.

After applying this patch series, in drivers/spi/spi.c file replace the 
following code snippet in __spi_add_device( ) function defination.

if (ctlr->cs_gpiods) {
        for (idx = 0; idx < SPI_CS_CNT_MAX; idx++)
                spi_set_csgpiod(spi, idx, ctlr->cs_gpiods[spi_get_chipselect(spi, idx)]);
}

with the below code snippet

if (ctlr->cs_gpiods) {
        for (idx = 0; idx < SPI_CS_CNT_MAX; idx++) {
                if (!(idx != 0 && !spi_get_chipselect(spi, idx)))
                        spi_set_csgpiod(spi, idx, ctlr->cs_gpiods[spi_get_chipselect(spi, idx)]);
        }
} 

then re-run your test.

Regards,
Amit
> 
> Thanks,
> 
> Stefan
> 
> >
> >> Thanks,
> >> Stefan Binding
> >>
> >>> Signed-off-by: Amit Kumar Mahapatra <amit.kumar-
> >> mahapatra@xxxxxxx>
> >>> ---
> >>>   drivers/spi/spi.c       | 226
> >> ++++++++++++++++++++++++++++------------
> >>>   include/linux/spi/spi.h |  32 ++++--
> >>>   2 files changed, 183 insertions(+), 75 deletions(-)
> >>>
> >>> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index
> >>> 9036d7a50674..04d7322170c4 100644
> >>> --- a/drivers/spi/spi.c
> >>> +++ b/drivers/spi/spi.c
> >>> @@ -612,10 +612,24 @@ static int spi_dev_check(struct device *dev,
> >>> void *data)  {
> >>>   	struct spi_device *spi = to_spi_device(dev);
> >>>   	struct spi_device *new_spi = data;
> >>> +	int idx, nw_idx;
> >>>
> >>> -	if (spi->controller == new_spi->controller &&
> >>> -	    spi_get_chipselect(spi, 0) == spi_get_chipselect(new_spi,
> >> 0))
> >>> -		return -EBUSY;
> >>> +	if (spi->controller == new_spi->controller) {
> >>> +		for (idx = 0; idx < SPI_CS_CNT_MAX; idx++) {
> >>> +			for (nw_idx = 0; nw_idx < SPI_CS_CNT_MAX;
> >>> nw_idx++) {
> >>> +				if ((idx != 0 &&
> >> !spi_get_chipselect(spi,
> >>> idx)) ||
> >>> +				    (nw_idx != 0 &&
> >>> !spi_get_chipselect(spi, nw_idx))) {
> >>> +					continue;
> >>> +				} else if (spi_get_chipselect(spi,
> >> idx) ==
> >>> +				    spi_get_chipselect(new_spi,
> >> nw_idx))
> >>> {
> >>> +					dev_err(dev,
> >>> +						"chipselect %d already
> >>> in use\n",
> >>> +
> >>> 	spi_get_chipselect(new_spi, nw_idx));
> >>> +					return -EBUSY;
> >>> +				}
> >>> +			}
> >>> +		}
> >>> +	}
> >>>   	return 0;
> >>>   }
> >>>
> >>> @@ -629,7 +643,7 @@ static int __spi_add_device(struct spi_device
> >>> *spi)
> >>>   {
> >>>   	struct spi_controller *ctlr = spi->controller;
> >>>   	struct device *dev = ctlr->dev.parent;
> >>> -	int status;
> >>> +	int status, idx;
> >>>
> >>>   	/*
> >>>   	 * We need to make sure there's no other device with this @@
> >>> -638,8
> >>> +652,6 @@ static int __spi_add_device(struct spi_device
> >>> *spi)
> >>>   	 */
> >>>   	status = bus_for_each_dev(&spi_bus_type, NULL, spi,
> >> spi_dev_check);
> >>>   	if (status) {
> >>> -		dev_err(dev, "chipselect %d already in use\n",
> >>> -				spi_get_chipselect(spi, 0));
> >>>   		return status;
> >>>   	}
> >>>
> >>> @@ -649,8 +661,10 @@ static int __spi_add_device(struct spi_device
> >>> *spi)
> >>>   		return -ENODEV;
> >>>   	}
> >>>
> >>> -	if (ctlr->cs_gpiods)
> >>> -		spi_set_csgpiod(spi, 0, ctlr-
> >>>> cs_gpiods[spi_get_chipselect(spi, 0)]);
> >>> +	if (ctlr->cs_gpiods) {
> >>> +		for (idx = 0; idx < SPI_CS_CNT_MAX; idx++)
> >>> +			spi_set_csgpiod(spi, idx, ctlr-
> >>>> cs_gpiods[spi_get_chipselect(spi, idx)]);
> >>> +	}
> >>>
> >>>   	/*
> >>>   	 * Drivers may modify this initial i/o setup, but will @@ -690,13
> >>> +704,15 @@ int spi_add_device(struct spi_device *spi)  {
> >>>   	struct spi_controller *ctlr = spi->controller;
> >>>   	struct device *dev = ctlr->dev.parent;
> >>> -	int status;
> >>> +	int status, idx;
> >>>
> >>> -	/* Chipselects are numbered 0..max; validate. */
> >>> -	if (spi_get_chipselect(spi, 0) >= ctlr->num_chipselect) {
> >>> -		dev_err(dev, "cs%d >= max %d\n",
> >>> spi_get_chipselect(spi, 0),
> >>> -			ctlr->num_chipselect);
> >>> -		return -EINVAL;
> >>> +	for (idx = 0; idx < SPI_CS_CNT_MAX; idx++) {
> >>> +		/* Chipselects are numbered 0..max; validate. */
> >>> +		if (spi_get_chipselect(spi, idx) >=
> >> ctlr->num_chipselect) {
> >>> +			dev_err(dev, "cs%d >= max %d\n",
> >>> spi_get_chipselect(spi, idx),
> >>> +				ctlr->num_chipselect);
> >>> +			return -EINVAL;
> >>> +		}
> >>>   	}
> >>>
> >>>   	/* Set the bus ID string */
> >>> @@ -713,12 +729,15 @@ static int spi_add_device_locked(struct
> >>> spi_device *spi)  {
> >>>   	struct spi_controller *ctlr = spi->controller;
> >>>   	struct device *dev = ctlr->dev.parent;
> >>> +	int idx;
> >>>
> >>> -	/* Chipselects are numbered 0..max; validate. */
> >>> -	if (spi_get_chipselect(spi, 0) >= ctlr->num_chipselect) {
> >>> -		dev_err(dev, "cs%d >= max %d\n",
> >>> spi_get_chipselect(spi, 0),
> >>> -			ctlr->num_chipselect);
> >>> -		return -EINVAL;
> >>> +	for (idx = 0; idx < SPI_CS_CNT_MAX; idx++) {
> >>> +		/* Chipselects are numbered 0..max; validate. */
> >>> +		if (spi_get_chipselect(spi, idx) >=
> >> ctlr->num_chipselect) {
> >>> +			dev_err(dev, "cs%d >= max %d\n",
> >>> spi_get_chipselect(spi, idx),
> >>> +				ctlr->num_chipselect);
> >>> +			return -EINVAL;
> >>> +		}
> >>>   	}
> >>>
> >>>   	/* Set the bus ID string */
> >>> @@ -966,58 +985,118 @@ static void spi_res_release(struct
> >>> spi_controller *ctlr, struct spi_message *mes  static void
> >>> spi_set_cs(struct spi_device *spi, bool enable, bool
> >> force)
> >>>   {
> >>>   	bool activate = enable;
> >>> +	u32 cs_num = __ffs(spi->cs_index_mask);
> >>> +	int idx;
> >>>
> >>>   	/*
> >>> -	 * Avoid calling into the driver (or doing delays) if the chip
> >> select
> >>> -	 * isn't actually changing from the last time this was called.
> >>> +	 * In parallel mode all the chip selects are
> >> asserted/de-asserted
> >>> +	 * at once
> >>>   	 */
> >>> -	if (!force && ((enable && spi->controller->last_cs ==
> >>> spi_get_chipselect(spi, 0)) ||
> >>> -		       (!enable && spi->controller->last_cs !=
> >>> spi_get_chipselect(spi, 0))) &&
> >>> -	    (spi->controller->last_cs_mode_high == (spi->mode &
> >>> SPI_CS_HIGH)))
> >>> -		return;
> >>> -
> >>> -	trace_spi_set_cs(spi, activate);
> >>> -
> >>> -	spi->controller->last_cs = enable ? spi_get_chipselect(spi, 0)
> >> : -1;
> >>> -	spi->controller->last_cs_mode_high = spi->mode &
> >>> SPI_CS_HIGH;
> >>> -
> >>> -	if ((spi_get_csgpiod(spi, 0) ||
> >> !spi->controller->set_cs_timing)
> >>> && !activate)
> >>> -		spi_delay_exec(&spi->cs_hold, NULL);
> >>> -
> >>> -	if (spi->mode & SPI_CS_HIGH)
> >>> -		enable = !enable;
> >>> +	if ((spi->cs_index_mask & SPI_PARALLEL_CS_MASK) ==
> >>> SPI_PARALLEL_CS_MASK) {
> >>> +		spi->controller->last_cs_mode_high = spi->mode &
> >>> SPI_CS_HIGH;
> >>> +
> >>> +		if ((spi_get_csgpiod(spi, 0) || !spi->controller-
> >>>> set_cs_timing) && !activate)
> >>> +			spi_delay_exec(&spi->cs_hold, NULL);
> >>> +
> >>> +		if (spi->mode & SPI_CS_HIGH)
> >>> +			enable = !enable;
> >>> +
> >>> +		if (spi_get_csgpiod(spi, 0) && spi_get_csgpiod(spi,
> >> 1)) {
> >>> +			if (!(spi->mode & SPI_NO_CS)) {
> >>> +				/*
> >>> +				 * Historically ACPI has no means of
> >> the
> >>> GPIO polarity and
> >>> +				 * thus the SPISerialBus() resource
> >>> defines it on the per-chip
> >>> +				 * basis. In order to avoid a chain of
> >>> negations, the GPIO
> >>> +				 * polarity is considered being Active
> >>> High. Even for the cases
> >>> +				 * when _DSD() is involved (in the
> >>> updated versions of ACPI)
> >>> +				 * the GPIO CS polarity must be
> >> defined
> >>> Active High to avoid
> >>> +				 * ambiguity. That's why we use
> >> enable,
> >>> that takes SPI_CS_HIGH
> >>> +				 * into account.
> >>> +				 */
> >>> +				if (has_acpi_companion(&spi->dev)) {
> >>> +					for (idx = 0; idx <
> >>> SPI_CS_CNT_MAX; idx++)
> >>> +
> >>> 	gpiod_set_value_cansleep(spi_get_csgpiod(spi, idx),
> >>> +
> >>> !enable);
> >>> +				} else {
> >>> +					for (idx = 0; idx <
> >>> SPI_CS_CNT_MAX; idx++)
> >>> +						/* Polarity handled by
> >>> GPIO library */
> >>> +
> >>> 	gpiod_set_value_cansleep(spi_get_csgpiod(spi, idx),
> >>> +
> >>> activate);
> >>> +				}
> >>> +			}
> >>> +			/* Some SPI masters need both GPIO CS &
> >>> slave_select */
> >>> +			if ((spi->controller->flags &
> >>> SPI_MASTER_GPIO_SS) &&
> >>> +			    spi->controller->set_cs)
> >>> +				spi->controller->set_cs(spi, !enable);
> >>> +		} else if (spi->controller->set_cs) {
> >>> +			spi->controller->set_cs(spi, !enable);
> >>> +		}
> >>>
> >>> -	if (spi_get_csgpiod(spi, 0)) {
> >>> -		if (!(spi->mode & SPI_NO_CS)) {
> >>> -			/*
> >>> -			 * Historically ACPI has no means of the GPIO
> >>> polarity and
> >>> -			 * thus the SPISerialBus() resource defines it
> >> on
> >>> the per-chip
> >>> -			 * basis. In order to avoid a chain of
> >> negations,
> >>> the GPIO
> >>> -			 * polarity is considered being Active High.
> >> Even
> >>> for the cases
> >>> -			 * when _DSD() is involved (in the updated
> >>> versions of ACPI)
> >>> -			 * the GPIO CS polarity must be defined Active
> >>> High to avoid
> >>> -			 * ambiguity. That's why we use enable, that
> >>> takes SPI_CS_HIGH
> >>> -			 * into account.
> >>> -			 */
> >>> -			if (has_acpi_companion(&spi->dev))
> >>> -
> >>> 	gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), !enable);
> >>> +		if (spi_get_csgpiod(spi, 0) || spi_get_csgpiod(spi, 1)
> >> ||
> >>> +		    !spi->controller->set_cs_timing) {
> >>> +			if (activate)
> >>> +				spi_delay_exec(&spi->cs_setup, NULL);
> >>>   			else
> >>> -				/* Polarity handled by GPIO library */
> >>> -
> >>> 	gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), activate);
> >>> +				spi_delay_exec(&spi->cs_inactive,
> >>> NULL);
> >>>   		}
> >>> -		/* Some SPI masters need both GPIO CS & slave_select
> >>> */
> >>> -		if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
> >>> -		    spi->controller->set_cs)
> >>> +	} else {
> >>> +		/*
> >>> +		 * Avoid calling into the driver (or doing delays) if
> >> the
> >>> chip select
> >>> +		 * isn't actually changing from the last time this was
> >>> called.
> >>> +		 */
> >>> +		if (!force && ((enable && spi->controller->last_cs ==
> >>> +				spi_get_chipselect(spi, cs_num)) ||
> >>> +				(!enable && spi->controller->last_cs
> >> !=
> >>> +				 spi_get_chipselect(spi, cs_num))) &&
> >>> +		    (spi->controller->last_cs_mode_high ==
> >>> +		     (spi->mode & SPI_CS_HIGH)))
> >>> +			return;
> >>> +
> >>> +		trace_spi_set_cs(spi, activate);
> >>> +
> >>> +		spi->controller->last_cs = enable ?
> >>> spi_get_chipselect(spi, cs_num) : -1;
> >>> +		spi->controller->last_cs_mode_high = spi->mode &
> >>> SPI_CS_HIGH;
> >>> +
> >>> +		if ((spi_get_csgpiod(spi, cs_num) || !spi->controller-
> >>>> set_cs_timing) && !activate)
> >>> +			spi_delay_exec(&spi->cs_hold, NULL);
> >>> +
> >>> +		if (spi->mode & SPI_CS_HIGH)
> >>> +			enable = !enable;
> >>> +
> >>> +		if (spi_get_csgpiod(spi, cs_num)) {
> >>> +			if (!(spi->mode & SPI_NO_CS)) {
> >>> +				/*
> >>> +				 * Historically ACPI has no means of
> >> the
> >>> GPIO polarity and
> >>> +				 * thus the SPISerialBus() resource
> >>> defines it on the per-chip
> >>> +				 * basis. In order to avoid a chain of
> >>> negations, the GPIO
> >>> +				 * polarity is considered being Active
> >>> High. Even for the cases
> >>> +				 * when _DSD() is involved (in the
> >>> updated versions of ACPI)
> >>> +				 * the GPIO CS polarity must be
> >> defined
> >>> Active High to avoid
> >>> +				 * ambiguity. That's why we use
> >> enable,
> >>> that takes SPI_CS_HIGH
> >>> +				 * into account.
> >>> +				 */
> >>> +				if (has_acpi_companion(&spi->dev))
> >>> +
> >>> 	gpiod_set_value_cansleep(spi_get_csgpiod(spi, cs_num),
> >>> +
> >>> !enable);
> >>> +				else
> >>> +					/* Polarity handled by GPIO
> >>> library */
> >>> +
> >>> 	gpiod_set_value_cansleep(spi_get_csgpiod(spi, cs_num),
> >>> +
> >>> activate);
> >>> +			}
> >>> +			/* Some SPI masters need both GPIO CS &
> >>> slave_select */
> >>> +			if ((spi->controller->flags &
> >>> SPI_MASTER_GPIO_SS) &&
> >>> +			    spi->controller->set_cs)
> >>> +				spi->controller->set_cs(spi, !enable);
> >>> +		} else if (spi->controller->set_cs) {
> >>>   			spi->controller->set_cs(spi, !enable);
> >>> -	} else if (spi->controller->set_cs) {
> >>> -		spi->controller->set_cs(spi, !enable);
> >>> -	}
> >>> +		}
> >>>
> >>> -	if (spi_get_csgpiod(spi, 0) ||
> >> !spi->controller->set_cs_timing) {
> >>> -		if (activate)
> >>> -			spi_delay_exec(&spi->cs_setup, NULL);
> >>> -		else
> >>> -			spi_delay_exec(&spi->cs_inactive, NULL);
> >>> +		if (spi_get_csgpiod(spi, cs_num) || !spi->controller-
> >>>> set_cs_timing) {
> >>> +			if (activate)
> >>> +				spi_delay_exec(&spi->cs_setup, NULL);
> >>> +			else
> >>> +				spi_delay_exec(&spi->cs_inactive,
> >>> NULL);
> >>> +		}
> >>>   	}
> >>>   }
> >>>
> >>> @@ -2246,8 +2325,8 @@ static void of_spi_parse_dt_cs_delay(struct
> >>> device_node *nc,  static int of_spi_parse_dt(struct spi_controller
> >>> *ctlr, struct
> >> spi_device
> >>> *spi,
> >>>   			   struct device_node *nc)
> >>>   {
> >>> -	u32 value;
> >>> -	int rc;
> >>> +	u32 value, cs[SPI_CS_CNT_MAX] = {0};
> >>> +	int rc, idx;
> >>>
> >>>   	/* Mode (clock phase/polarity/etc.) */
> >>>   	if (of_property_read_bool(nc, "spi-cpha")) @@ -2320,13 +2399,21
> >> @@
> >>> static int of_spi_parse_dt(struct spi_controller *ctlr, struct
> >>> spi_device *spi,
> >>>   	}
> >>>
> >>>   	/* Device address */
> >>> -	rc = of_property_read_u32(nc, "reg", &value);
> >>> -	if (rc) {
> >>> +	rc = of_property_read_variable_u32_array(nc, "reg", &cs[0], 1,
> >>> +						 SPI_CS_CNT_MAX);
> >>> +	if (rc < 0 || rc > ctlr->num_chipselect) {
> >>>   		dev_err(&ctlr->dev, "%pOF has no valid 'reg' property
> >> (%d)\n",
> >>>   			nc, rc);
> >>>   		return rc;
> >>> +	} else if ((of_property_read_bool(nc, "parallel-memories")) &&
> >>> +		   (!(ctlr->flags & SPI_CONTROLLER_MULTI_CS))) {
> >>> +		dev_err(&ctlr->dev, "SPI controller doesn't support
> >> multi
> >>> CS\n");
> >>> +		return -EINVAL;
> >>>   	}
> >>> -	spi_set_chipselect(spi, 0, value);
> >>> +	for (idx = 0; idx < rc; idx++)
> >>> +		spi_set_chipselect(spi, idx, cs[idx]);
> >>> +	/* By default set the spi->cs_index_mask as 1 */
> >>> +	spi->cs_index_mask = 0x01;
> >>>
> >>>   	/* Device speed */
> >>>   	if (!of_property_read_u32(nc, "spi-max-frequency", &value)) @@
> >>> -3907,7 +3994,8 @@ static int __spi_validate(struct spi_device *spi,
> >>> struct spi_message *message)
> >>>   	 * cs_change is set for each transfer.
> >>>   	 */
> >>>   	if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits &
> >>> SPI_CS_WORD) ||
> >>> -					  spi_get_csgpiod(spi, 0))) {
> >>> +					  spi_get_csgpiod(spi, 0) ||
> >>> +					  spi_get_csgpiod(spi, 1))) {
> >>>   		size_t maxsize;
> >>>   		int ret;
> >>>
> >>> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index
> >>> 873ced6ae4ca..6453b246e0af 100644
> >>> --- a/include/linux/spi/spi.h
> >>> +++ b/include/linux/spi/spi.h
> >>> @@ -19,6 +19,11 @@
> >>>   #include <linux/acpi.h>
> >>>   #include <linux/u64_stats_sync.h>
> >>>
> >>> +/* Max no. of CS supported per spi device */ #define SPI_CS_CNT_MAX
> >>> +2
> >>> +
> >>> +/* chip select mask */
> >>> +#define SPI_PARALLEL_CS_MASK	(BIT(0) | BIT(1))
> >>>   struct dma_chan;
> >>>   struct software_node;
> >>>   struct ptp_system_timestamp;
> >>> @@ -166,6 +171,7 @@ extern void
> >>> spi_transfer_cs_change_delay_exec(struct spi_message *msg,
> >>>    *	deasserted. If @cs_change_delay is used from @spi_transfer,
> >>> then the
> >>>    *	two delays will be added up.
> >>>    * @pcpu_statistics: statistics for the spi_device
> >>> + * @cs_index_mask: Bit mask of the active chipselect(s) in the
> >>> chipselect array
> >>>    *
> >>>    * A @spi_device is used to interchange data between an SPI slave
> >>>    * (usually a discrete chip) and CPU memory.
> >>> @@ -181,7 +187,7 @@ struct spi_device {
> >>>   	struct spi_controller	*controller;
> >>>   	struct spi_controller	*master;	/* Compatibility layer
> >> */
> >>>   	u32			max_speed_hz;
> >>> -	u8			chip_select;
> >>> +	u8			chip_select[SPI_CS_CNT_MAX];
> >>>   	u8			bits_per_word;
> >>>   	bool			rt;
> >>>   #define SPI_NO_TX	BIT(31)		/* No transmit wire */
> >>> @@ -202,7 +208,7 @@ struct spi_device {
> >>>   	void			*controller_data;
> >>>   	char			modalias[SPI_NAME_SIZE];
> >>>   	const char		*driver_override;
> >>> -	struct gpio_desc	*cs_gpiod;	/* Chip select gpio
> >> desc
> >>> */
> >>> +	struct gpio_desc	*cs_gpiod[SPI_CS_CNT_MAX];	/*
> >> Chip
> >>> select gpio desc */
> >>>   	struct spi_delay	word_delay; /* Inter-word delay */
> >>>   	/* CS delays */
> >>>   	struct spi_delay	cs_setup;
> >>> @@ -212,6 +218,13 @@ struct spi_device {
> >>>   	/* The statistics */
> >>>   	struct spi_statistics __percpu	*pcpu_statistics;
> >>>
> >>> +	/* Bit mask of the chipselect(s) that the driver need to use
> >> from
> >>> +	 * the chipselect array.When the controller is capable to
> >> handle
> >>> +	 * multiple chip selects & memories are connected in parallel
> >>> +	 * then more than one bit need to be set in cs_index_mask.
> >>> +	 */
> >>> +	u32			cs_index_mask : SPI_CS_CNT_MAX;
> >>> +
> >>>   	/*
> >>>   	 * likely need more hooks for more protocol options affecting how
> >>>   	 * the controller talks to each chip, like:
> >>> @@ -268,22 +281,22 @@ static inline void *spi_get_drvdata(const
> >>> struct spi_device *spi)
> >>>
> >>>   static inline u8 spi_get_chipselect(const struct spi_device *spi,
> >> u8 idx)
> >>>   {
> >>> -	return spi->chip_select;
> >>> +	return spi->chip_select[idx];
> >>>   }
> >>>
> >>>   static inline void spi_set_chipselect(struct spi_device *spi, u8
> >> idx, u8
> >>> chipselect)
> >>>   {
> >>> -	spi->chip_select = chipselect;
> >>> +	spi->chip_select[idx] = chipselect;
> >>>   }
> >>>
> >>>   static inline struct gpio_desc *spi_get_csgpiod(const struct
> >> spi_device
> >>> *spi, u8 idx)
> >>>   {
> >>> -	return spi->cs_gpiod;
> >>> +	return spi->cs_gpiod[idx];
> >>>   }
> >>>
> >>>   static inline void spi_set_csgpiod(struct spi_device *spi, u8 idx,
> >> struct
> >>> gpio_desc *csgpiod)
> >>>   {
> >>> -	spi->cs_gpiod = csgpiod;
> >>> +	spi->cs_gpiod[idx] = csgpiod;
> >>>   }
> >>>
> >>>   /**
> >>> @@ -388,6 +401,8 @@ extern struct spi_device
> >>> *spi_new_ancillary_device(struct spi_device *spi, u8 ch
> >>>    * @bus_lock_spinlock: spinlock for SPI bus locking
> >>>    * @bus_lock_mutex: mutex for exclusion of multiple callers
> >>>    * @bus_lock_flag: indicates that the SPI bus is locked for
> >> exclusive use
> >>> + * @multi_cs_cap: indicates that the SPI Controller can
> >> assert/de-assert
> >>> + *	more than one chip select at once.
> >>>    * @setup: updates the device mode and clocking records used by a
> >>>    *	device's SPI controller; protocol code may call this.  This
> >>>    *	must fail if an unrecognized or unsupported mode is requested.
> >>> @@ -554,6 +569,11 @@ struct spi_controller {
> >>>   #define SPI_CONTROLLER_MUST_TX		BIT(4)	/* Requires tx
> >>> */
> >>>
> >>>   #define SPI_MASTER_GPIO_SS		BIT(5)	/* GPIO CS must
> >> select
> >>> slave */
> >>> +	/*
> >>> +	 * The spi-controller has multi chip select capability and can
> >>> +	 * assert/de-assert more than one chip select at once.
> >>> +	 */
> >>> +#define SPI_CONTROLLER_MULTI_CS		BIT(6)
> >>>
> >>>   	/* Flag indicating if the allocation of this struct is devres-
> >>> managed */
> >>>   	bool			devm_allocated;
> >>> --
> >>> 2.17.1