[POWERPC] cpm_uart: Allocate DPRAM memory for SMC ports on CPM2-based platforms.

This patch allocates parameter RAM for SMC serial ports without relying on
previous initialisation by a boot loader or a wrapper layer.

SMC parameter RAM on CPM2-based platforms can be allocated anywhere in the
general-purpose areas of the dual-port RAM. The current code relies on the
boot loader to allocate a section of general-purpose CPM RAM and gets the
section address from the device tree.

This patch modifies the device tree address usage to reference the SMC
parameter RAM base pointer instead of a pre-allocated RAM section and
allocates memory from the CPM dual-port RAM when initialising the SMC port.
CPM1-based platforms are not affected.

Signed-off-by: Laurent Pinchart <[e-mail]>
Acked-by: Scott Wood <[e-mail]>
Signed-off-by: Kumar Gala <[e-mail]>

drivers/serial/cpm_uart/cpm_uart.h

···
 
 /* these are located in their respective files */
 void cpm_line_cr_cmd(struct uart_cpm_port *port, int cmd);
+void __iomem *cpm_uart_map_pram(struct uart_cpm_port *port,
+				struct device_node *np);
+void cpm_uart_unmap_pram(struct uart_cpm_port *port, void __iomem *pram);
 int cpm_uart_init_portdesc(void);
 int cpm_uart_allocbuf(struct uart_cpm_port *pinfo, unsigned int is_con);
 void cpm_uart_freebuf(struct uart_cpm_port *pinfo);

drivers/serial/cpm_uart/cpm_uart_core.c

···
 	if (!mem)
 		return -ENOMEM;
 
-	pram = of_iomap(np, 1);
-	if (!pram) {
-		ret = -ENOMEM;
-		goto out_mem;
-	}
-
 	if (of_device_is_compatible(np, "fsl,cpm1-scc-uart") ||
 	    of_device_is_compatible(np, "fsl,cpm2-scc-uart")) {
 		pinfo->sccp = mem;
-		pinfo->sccup = pram;
+		pinfo->sccup = pram = cpm_uart_map_pram(pinfo, np);
 	} else if (of_device_is_compatible(np, "fsl,cpm1-smc-uart") ||
 	           of_device_is_compatible(np, "fsl,cpm2-smc-uart")) {
 		pinfo->flags |= FLAG_SMC;
 		pinfo->smcp = mem;
-		pinfo->smcup = pram;
+		pinfo->smcup = pram = cpm_uart_map_pram(pinfo, np);
 	} else {
 		ret = -ENODEV;
-		goto out_pram;
+		goto out_mem;
+	}
+
+	if (!pram) {
+		ret = -ENOMEM;
+		goto out_mem;
 	}
 
 	pinfo->tx_nrfifos = TX_NUM_FIFO;
···
 	return cpm_uart_request_port(&pinfo->port);
 
 out_pram:
-	iounmap(pram);
+	cpm_uart_unmap_pram(pinfo, pram);
 out_mem:
 	iounmap(mem);
 	return ret;

drivers/serial/cpm_uart/cpm_uart_cpm1.c

···
 #include <linux/serial_core.h>
 #include <linux/kernel.h>
 
+#include <linux/of.h>
+
 #include "cpm_uart.h"
 
 /**************************************************************/
···
 {
 	cpm_command(port->command, cmd);
 }
+
+void __iomem *cpm_uart_map_pram(struct uart_cpm_port *port,
+				struct device_node *np)
+{
+	return of_iomap(np, 1);
+}
+
+void cpm_uart_unmap_pram(struct uart_cpm_port *port, void __iomem *pram)
+{
+	iounmap(pram);
+}
+
 #else
 void cpm_line_cr_cmd(struct uart_cpm_port *port, int cmd)
 {

drivers/serial/cpm_uart/cpm_uart_cpm2.c

···
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <asm/fs_pd.h>
+#ifdef CONFIG_PPC_CPM_NEW_BINDING
+#include <asm/prom.h>
+#endif
 
 #include <linux/serial_core.h>
 #include <linux/kernel.h>
···
 {
 	cpm_command(port->command, cmd);
 }
+
+void __iomem *cpm_uart_map_pram(struct uart_cpm_port *port,
+				struct device_node *np)
+{
+	void __iomem *pram;
+	unsigned long offset;
+	struct resource res;
+	unsigned long len;
+
+	/* Don't remap parameter RAM if it has already been initialized
+	 * during console setup.
+	 */
+	if (IS_SMC(port) && port->smcup)
+		return port->smcup;
+	else if (!IS_SMC(port) && port->sccup)
+		return port->sccup;
+
+	if (of_address_to_resource(np, 1, &res))
+		return NULL;
+
+	len = 1 + res.end - res.start;
+	pram = ioremap(res.start, len);
+	if (!pram)
+		return NULL;
+
+	if (!IS_SMC(port))
+		return pram;
+
+	if (len != 2) {
+		printk(KERN_WARNING "cpm_uart[%d]: device tree references "
+			"SMC pram, using boot loader/wrapper pram mapping. "
+			"Please fix your device tree to reference the pram "
+			"base register instead.\n",
+			port->port.line);
+		return pram;
+	}
+
+	offset = cpm_dpalloc(PROFF_SMC_SIZE, 64);
+	out_be16(pram, offset);
+	iounmap(pram);
+	return cpm_muram_addr(offset);
+}
+
+void cpm_uart_unmap_pram(struct uart_cpm_port *port, void __iomem *pram)
+{
+	if (!IS_SMC(port))
+		iounmap(pram);
+}
+
 #else
 void cpm_line_cr_cmd(struct uart_cpm_port *port, int cmd)
 {