[PATCH v5 1/8] serial: 8250_dw: select port setup through platform data

[James Hilliard]

Select feature discovery and DMA attachment through a platform-data setup
callback. The generic callback probes the optional registers and attaches
DMA when a FIFO size is available. Integrations with a fixed configuration
can supply their own setup before the port is registered. Allow setup to
return an error so integrations can reject invalid configuration before
registration.

Replace skip_autocfg with the Octeon setup selection. Octeon is a 64-bit
platform and continues to skip optional-register probing while retaining
its DMA setup. Select the DMA setup helper directly for this integration.
Keep generic setup for devices without matched platform data as well.

Signed-off-by: James Hilliard <james.hilliard1 at gmail.com>
---
 drivers/tty/serial/8250/8250_dw.c | 41 ++++++++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 9cbe076463e0..a546cf2de7b6 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -64,6 +64,7 @@ struct dw8250_platform_data {
 	u8 usr_reg;
 	u32 cpr_value;
 	unsigned int quirks;
+	int (*setup)(struct uart_port *p);
 };
 
 struct dw8250_data {
@@ -76,7 +77,6 @@ struct dw8250_data {
 	struct clk		*pclk;
 	struct reset_control	*rst;
 
-	unsigned int		skip_autocfg:1;
 	unsigned int		uart_16550_compatible:1;
 	unsigned int		in_idle:1;
 
@@ -596,7 +596,6 @@ static void dw8250_quirks(struct uart_port *p, struct dw8250_data *data)
 		p->serial_out = dw8250_serial_outq;
 		p->flags = UPF_SKIP_TEST | UPF_SHARE_IRQ | UPF_FIXED_TYPE;
 		p->type = PORT_OCTEON;
-		data->skip_autocfg = true;
 	}
 #endif
 
@@ -631,6 +630,28 @@ static void dw8250_shutdown(struct uart_port *port)
 	d->no_int_count = 0;
 }
 
+static int dw8250_setup_dma(struct uart_port *p)
+{
+	struct dw8250_data *data = to_dw8250_data(p->private_data);
+	struct uart_8250_port *up = up_to_u8250p(p);
+
+	/* DMA setup requires a FIFO */
+	if (!p->fifosize)
+		return 0;
+
+	data->data.dma.rxconf.src_maxburst = p->fifosize / 4;
+	data->data.dma.txconf.dst_maxburst = p->fifosize / 4;
+	up->dma = &data->data.dma;
+
+	return 0;
+}
+
+static int dw8250_setup(struct uart_port *p)
+{
+	dw8250_setup_port(p);
+	return dw8250_setup_dma(p);
+}
+
 static int dw8250_probe(struct platform_device *pdev)
 {
 	struct uart_8250_port uart = {}, *up = &uart;
@@ -765,19 +786,16 @@ static int dw8250_probe(struct platform_device *pdev)
 
 	dw8250_setup_dma_filter(p, data);
 
-	if (!data->skip_autocfg)
-		dw8250_setup_port(p);
+	if (data->pdata && data->pdata->setup)
+		err = data->pdata->setup(p);
+	else
+		err = dw8250_setup(p);
+	if (err)
+		return err;
 
 	/* Use the BUSY-safe sequence for both integer and fractional divisors. */
 	p->set_divisor = dw8250_set_divisor;
 
-	/* If we have a valid fifosize, try hooking up DMA */
-	if (p->fifosize) {
-		data->data.dma.rxconf.src_maxburst = p->fifosize / 4;
-		data->data.dma.txconf.dst_maxburst = p->fifosize / 4;
-		up->dma = &data->data.dma;
-	}
-
 	data->data.uport = serial8250_register_8250_port(up);
 	if (IS_ERR(data->data.uport))
 		return PTR_ERR(data->data.uport);
@@ -860,6 +878,7 @@ static const struct dw8250_platform_data dw8250_dw_apb = {
 static const struct dw8250_platform_data dw8250_octeon_3860_data = {
 	.usr_reg = OCTEON_UART_USR,
 	.quirks = DW_UART_QUIRK_OCTEON,
+	.setup = dw8250_setup_dma,
 };
 
 static const struct dw8250_platform_data dw8250_armada_38x_data = {

-- 
2.53.0