Re: [PATCH v2 6/6] serial: exar: Add support for IOT2040 device

From: Jan Kiszka
Date: Thu May 18 2017 - 13:23:45 EST

On 2017-05-18 18:58, Jan Kiszka wrote:
> On 2017-05-18 18:39, Jan Kiszka wrote:
>> On 2017-05-18 18:33, Andy Shevchenko wrote:
>>> On Thu, May 18, 2017 at 5:59 PM, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote:
>>>> This implements the setup of RS232 and the switch-over to RS485 or RS422
>>>> for the Siemens IOT2040. That uses an EXAR XR17V352 with external logic
>>>> to switch between the different modes. The external logic is controlled
>>>> via MPIO pins of the EXAR controller.
>>>>
>>>> Only pin 10 can be exported as GPIO on the IOT2040. It is connected to
>>>> an LED.
>>>>
>>>> As the XR17V352 used on the IOT2040 is not equipped with an external
>>>> EEPROM, it cannot present itself as IOT2040-variant via subvendor/
>>>> subdevice IDs. Thus, we have to check via DMI for the target platform.
>>>>
>>>> Co-developed with Sascha Weisenberger.
>>>
>>> Few nits below and one comment that should be addressed.
>>>
>>>> +#define UART_EXAR_RS485_DLY(x) (x << 4)
>>>
>>> ((x) << 4)
>>
>> Yep.
>>
>>>
>>>> +static bool is_iot2040;
>>>
>>> No, please, use driver data of DMI and hide this in corresponding structure.
>>> Or even assign port->port.rs485_config in the callback function.
>>>
>>> Moreover, can't you use port->port.rs485_config != NULL instead?
>>
>> There are two cases to be handled on IOT2040: the setting of the
>> rs485_config and the different setup of the GPIOs, but the latter at a
>> specific point in the initialization only. So I don't see yet how
>> driver_data could come into play and help.
>>
>
> OK, got - hacking...

It looks like this now (will resent as part of v3, just waiting for
further comments):

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index d9c52288d6c9..01826c094515 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -9,6 +9,7 @@
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License.
*/
+#include <linux/dmi.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -61,8 +62,50 @@
#define UART_EXAR_MPIOSEL_15_8 0x99 /* MPIOSEL[15:8] */
#define UART_EXAR_MPIOOD_15_8 0x9a /* MPIOOD[15:8] */

+#define UART_EXAR_RS485_DLY(x) ((x) << 4)
+
+/*
+ * IOT2040 MPIO wiring semantics:
+ *
+ * MPIO Port Function
+ * ---- ---- --------
+ * 0 2 Mode bit 0
+ * 1 2 Mode bit 1
+ * 2 2 Terminate bus
+ * 3 - <reserved>
+ * 4 3 Mode bit 0
+ * 5 3 Mode bit 1
+ * 6 3 Terminate bus
+ * 7 - <reserved>
+ * 8 2 Enable
+ * 9 3 Enable
+ * 10 - Red LED
+ * 11..15 - <unused>
+ */
+
+/* IOT2040 MPIOs 0..7 */
+#define IOT2040_UART_MODE_RS232 0x01
+#define IOT2040_UART_MODE_RS485 0x02
+#define IOT2040_UART_MODE_RS422 0x03
+#define IOT2040_UART_TERMINATE_BUS 0x04
+
+#define IOT2040_UART1_MASK 0x0f
+#define IOT2040_UART2_SHIFT 4
+
+#define IOT2040_UARTS_DEFAULT_MODE 0x11 /* both RS232 */
+#define IOT2040_UARTS_GPIO_LO_MODE 0x88 /* reserved pins as input */
+
+/* IOT2040 MPIOs 8..15 */
+#define IOT2040_UARTS_ENABLE 0x03
+#define IOT2040_UARTS_GPIO_HI_MODE 0xF8 /* enable & LED as outputs */
+
struct exar8250;

+struct exar8250_platform {
+ int (*rs485_config)(struct uart_port *, struct serial_rs485 *);
+ int (*register_gpio)(struct pci_dev *, struct uart_8250_port *);
+};
+
/**
* struct exar8250_board - board information
* @num_ports: number of serial ports
@@ -189,7 +232,7 @@ static void setup_gpio(u8 __iomem *p)
}

static void *
-xr17v35x_register_gpio(struct pci_dev *pcidev, unsigned int first_gpio,
+__xr17v35x_register_gpio(struct pci_dev *pcidev, unsigned int first_gpio,
unsigned int ngpio)
{
struct platform_device *pdev;
@@ -212,17 +255,113 @@ xr17v35x_register_gpio(struct pci_dev *pcidev, unsigned int first_gpio,
return pdev;
}

+static int xr17v35x_register_gpio(struct pci_dev *pcidev,
+ struct uart_8250_port *port)
+{
+ port->port.private_data = __xr17v35x_register_gpio(pcidev, 0, 16);
+
+ return 0;
+}
+
+static int iot2040_rs485_config(struct uart_port *port,
+ struct serial_rs485 *rs485)
+{
+ bool is_rs485 = !!(rs485->flags & SER_RS485_ENABLED);
+ u8 __iomem *p = port->membase;
+ u8 mask = IOT2040_UART1_MASK;
+ u8 mode, value;
+
+ if (is_rs485) {
+ if (rs485->flags & SER_RS485_RX_DURING_TX)
+ mode = IOT2040_UART_MODE_RS422;
+ else
+ mode = IOT2040_UART_MODE_RS485;
+
+ if (rs485->flags & SER_RS485_TERMINATE_BUS)
+ mode |= IOT2040_UART_TERMINATE_BUS;
+ } else {
+ mode = IOT2040_UART_MODE_RS232;
+ }
+
+ if (port->line == 3) {
+ mask <<= IOT2040_UART2_SHIFT;
+ mode <<= IOT2040_UART2_SHIFT;
+ }
+
+ value = readb(p + UART_EXAR_MPIOLVL_7_0);
+ value &= ~mask;
+ value |= mode;
+ writeb(value, p + UART_EXAR_MPIOLVL_7_0);
+
+ value = readb(p + UART_EXAR_FCTR);
+ if (is_rs485)
+ value |= UART_FCTR_EXAR_485;
+ else
+ value &= ~UART_FCTR_EXAR_485;
+ writeb(value, p + UART_EXAR_FCTR);
+
+ if (is_rs485)
+ writeb(UART_EXAR_RS485_DLY(4), p + UART_MSR);
+
+ return 0;
+}
+
+static int iot2040_register_gpio(struct pci_dev *pcidev,
+ struct uart_8250_port *port)
+{
+ u8 __iomem *p = port->port.membase;
+
+ writeb(IOT2040_UARTS_DEFAULT_MODE, p + UART_EXAR_MPIOLVL_7_0);
+ writeb(IOT2040_UARTS_GPIO_LO_MODE, p + UART_EXAR_MPIOSEL_7_0);
+ writeb(IOT2040_UARTS_ENABLE, p + UART_EXAR_MPIOLVL_15_8);
+ writeb(IOT2040_UARTS_GPIO_HI_MODE, p + UART_EXAR_MPIOSEL_15_8);
+
+ port->port.private_data = __xr17v35x_register_gpio(pcidev, 10, 1);
+
+ return 0;
+}
+
+static const struct exar8250_platform exar8250_default_platform = {
+ .register_gpio = xr17v35x_register_gpio,
+};
+
+static const struct exar8250_platform iot2040_platform = {
+ .rs485_config = iot2040_rs485_config,
+ .register_gpio = iot2040_register_gpio,
+};
+
+static const struct dmi_system_id exar_platforms[] = {
+ {
+ .ident = "IOT2040",
+ .matches = {
+ DMI_MATCH(DMI_BOARD_NAME, "SIMATIC IOT2000"),
+ DMI_MATCH(DMI_BOARD_ASSET_TAG, "6ES7647-0AA00-1YA2"),
+ },
+ .driver_data = (void *)&iot2040_platform,
+ }
+};
+
static int
pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev,
struct uart_8250_port *port, int idx)
{
const struct exar8250_board *board = priv->board;
+ const struct exar8250_platform *platform;
+ const struct dmi_system_id *dmi_match;
unsigned int offset = idx * 0x400;
unsigned int baud = 7812500;
u8 __iomem *p;
int ret;

+ dmi_match = dmi_first_match(exar_platforms);
+ if (dmi_match)
+ platform = dmi_match->driver_data;
+ else
+ platform = &exar8250_default_platform;
+
port->port.uartclk = baud * 16;
+ port->port.rs485_config = platform->rs485_config;
+
/*
* Setup the uart clock for the devices on expansion slot to
* half the clock speed of the main chip (which is 125MHz)
@@ -245,10 +384,10 @@ pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev,
/* Setup Multipurpose Input/Output pins. */
setup_gpio(p);

- port->port.private_data = xr17v35x_register_gpio(pcidev, 0, 16);
+ ret = platform->register_gpio(pcidev, port);
}

- return 0;
+ return ret;
}

static void pci_xr17v35x_exit(struct pci_dev *pcidev)
--
2.12.