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[PATCH v2 2/4] tty/8250_dw: Add support for OCTEON UARTS.

To: linux-mips@linux-mips.org, ralf@linux-mips.org, Jamie Iles <jamie@jamieiles.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jslaby@suse.cz>, linux-serial@vger.kernel.org
Subject: [PATCH v2 2/4] tty/8250_dw: Add support for OCTEON UARTS.
From: David Daney <ddaney.cavm@gmail.com>
Date: Wed, 19 Jun 2013 14:37:27 -0700
Cc: linux-kernel@vger.kernel.org, David Daney <david.daney@cavium.com>, Arnd Bergmann <arnd@arndb.de>, Heikki Krogerus <heikki.krogerus@linux.intel.com>
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From: David Daney <david.daney@cavium.com>

A few differences needed by OCTEON:

o These are DWC UARTS, but have USR at a different offset.

o Internal SoC buses require reading back from registers to maintain
  write ordering.

o 8250 on OCTEON appears with 64-bit wide registers, so when using
  readb/writeb in big endian mode we have to adjust the membase to hit
  the proper part of the register.

o No UCV register, so we hard code some properties.

Because OCTEON doesn't have a UCV register, I change where
dw8250_setup_port(), which reads the UCV, is called by pushing it in
to the OF and ACPI probe functions, and move unchanged
dw8250_setup_port() earlier in the file.

Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 drivers/tty/serial/8250/8250_dw.c | 108 ++++++++++++++++++++++++--------------
 1 file changed, 69 insertions(+), 39 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c 
b/drivers/tty/serial/8250/8250_dw.c
index d07b6af..76a8daa 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -29,6 +29,8 @@
 #include <linux/clk.h>
 #include <linux/pm_runtime.h>
 
+#include <asm/byteorder.h>
+
 #include "8250.h"
 
 /* Offsets for the DesignWare specific registers */
@@ -57,6 +59,7 @@ struct dw8250_data {
        int             last_lcr;
        int             line;
        struct clk      *clk;
+       u8              usr_reg;
 };
 
 static void dw8250_serial_out(struct uart_port *p, int offset, int value)
@@ -77,6 +80,13 @@ static unsigned int dw8250_serial_in(struct uart_port *p, 
int offset)
        return readb(p->membase + offset);
 }
 
+/* Read Back (rb) version to ensure register access ording. */
+static void dw8250_serial_out_rb(struct uart_port *p, int offset, int value)
+{
+       dw8250_serial_out(p, offset, value);
+       dw8250_serial_in(p, UART_LCR);
+}
+
 static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
 {
        struct dw8250_data *d = p->private_data;
@@ -104,7 +114,7 @@ static int dw8250_handle_irq(struct uart_port *p)
                return 1;
        } else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
                /* Clear the USR and write the LCR again. */
-               (void)p->serial_in(p, DW_UART_USR);
+               (void)p->serial_in(p, d->usr_reg);
                p->serial_out(p, UART_LCR, d->last_lcr);
 
                return 1;
@@ -125,12 +135,60 @@ dw8250_do_pm(struct uart_port *port, unsigned int state, 
unsigned int old)
                pm_runtime_put_sync_suspend(port->dev);
 }
 
-static int dw8250_probe_of(struct uart_port *p)
+static void dw8250_setup_port(struct uart_8250_port *up)
+{
+       struct uart_port        *p = &up->port;
+       u32                     reg = readl(p->membase + DW_UART_UCV);
+
+       /*
+        * If the Component Version Register returns zero, we know that
+        * ADDITIONAL_FEATURES are not enabled. No need to go any further.
+        */
+       if (!reg)
+               return;
+
+       dev_dbg_ratelimited(p->dev, "Designware UART version %c.%c%c\n",
+               (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);
+
+       reg = readl(p->membase + DW_UART_CPR);
+       if (!reg)
+               return;
+
+       /* Select the type based on fifo */
+       if (reg & DW_UART_CPR_FIFO_MODE) {
+               p->type = PORT_16550A;
+               p->flags |= UPF_FIXED_TYPE;
+               p->fifosize = DW_UART_CPR_FIFO_SIZE(reg);
+               up->tx_loadsz = p->fifosize;
+               up->capabilities = UART_CAP_FIFO;
+       }
+
+       if (reg & DW_UART_CPR_AFCE_MODE)
+               up->capabilities |= UART_CAP_AFE;
+}
+
+static int dw8250_probe_of(struct uart_port *p,
+                          struct dw8250_data *data)
 {
        struct device_node      *np = p->dev->of_node;
        u32                     val;
-
-       if (!of_property_read_u32(np, "reg-io-width", &val)) {
+       bool has_ucv = true;
+
+       if (of_device_is_compatible(np, "cavium,octeon-3860-uart")) {
+#ifdef __BIG_ENDIAN
+               /*
+                * Low order bits of these 64-bit registers, when
+                * accessed as a byte, are 7 bytes further down in the
+                * address space in big endian mode.
+                */
+               p->membase += 7;
+#endif
+               p->serial_out = dw8250_serial_out_rb;
+               p->flags = ASYNC_SKIP_TEST | UPF_SHARE_IRQ | UPF_FIXED_TYPE;
+               p->type = PORT_OCTEON;
+               data->usr_reg = 0x27;
+               has_ucv = false;
+       } else if (!of_property_read_u32(np, "reg-io-width", &val)) {
                switch (val) {
                case 1:
                        break;
@@ -144,6 +202,8 @@ static int dw8250_probe_of(struct uart_port *p)
                        return -EINVAL;
                }
        }
+       if (has_ucv)
+               dw8250_setup_port(container_of(p, struct uart_8250_port, port));
 
        if (!of_property_read_u32(np, "reg-shift", &val))
                p->regshift = val;
@@ -168,6 +228,8 @@ static int dw8250_probe_acpi(struct uart_8250_port *up)
        const struct acpi_device_id *id;
        struct uart_port *p = &up->port;
 
+       dw8250_setup_port(up);
+
        id = acpi_match_device(p->dev->driver->acpi_match_table, p->dev);
        if (!id)
                return -ENODEV;
@@ -196,38 +258,6 @@ static inline int dw8250_probe_acpi(struct uart_8250_port 
*up)
 }
 #endif /* CONFIG_ACPI */
 
-static void dw8250_setup_port(struct uart_8250_port *up)
-{
-       struct uart_port        *p = &up->port;
-       u32                     reg = readl(p->membase + DW_UART_UCV);
-
-       /*
-        * If the Component Version Register returns zero, we know that
-        * ADDITIONAL_FEATURES are not enabled. No need to go any further.
-        */
-       if (!reg)
-               return;
-
-       dev_dbg_ratelimited(p->dev, "Designware UART version %c.%c%c\n",
-               (reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);
-
-       reg = readl(p->membase + DW_UART_CPR);
-       if (!reg)
-               return;
-
-       /* Select the type based on fifo */
-       if (reg & DW_UART_CPR_FIFO_MODE) {
-               p->type = PORT_16550A;
-               p->flags |= UPF_FIXED_TYPE;
-               p->fifosize = DW_UART_CPR_FIFO_SIZE(reg);
-               up->tx_loadsz = p->fifosize;
-               up->capabilities = UART_CAP_FIFO;
-       }
-
-       if (reg & DW_UART_CPR_AFCE_MODE)
-               up->capabilities |= UART_CAP_AFE;
-}
-
 static int dw8250_probe(struct platform_device *pdev)
 {
        struct uart_8250_port uart = {};
@@ -259,6 +289,7 @@ static int dw8250_probe(struct platform_device *pdev)
        if (!data)
                return -ENOMEM;
 
+       data->usr_reg = DW_UART_USR;
        data->clk = devm_clk_get(&pdev->dev, NULL);
        if (!IS_ERR(data->clk)) {
                clk_prepare_enable(data->clk);
@@ -270,10 +301,8 @@ static int dw8250_probe(struct platform_device *pdev)
        uart.port.serial_out = dw8250_serial_out;
        uart.port.private_data = data;
 
-       dw8250_setup_port(&uart);
-
        if (pdev->dev.of_node) {
-               err = dw8250_probe_of(&uart.port);
+               err = dw8250_probe_of(&uart.port, data);
                if (err)
                        return err;
        } else if (ACPI_HANDLE(&pdev->dev)) {
@@ -362,6 +391,7 @@ static const struct dev_pm_ops dw8250_pm_ops = {
 
 static const struct of_device_id dw8250_of_match[] = {
        { .compatible = "snps,dw-apb-uart" },
+       { .compatible = "cavium,octeon-3860-uart" },
        { /* Sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, dw8250_of_match);
-- 
1.7.11.7


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