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

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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

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
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