cleanup the clock API use of the UART driver which is shared among the
MPC512x and the MPC5200 platforms
- get, prepare, and enable the MCLK during port allocation; disable,
unprepare and put the MCLK upon port release; hold a reference to the
clock over the period of use; check for and propagate enable errors
- fix a buffer overflow for clock names with two digit PSC index numbers
- stick with the PPC_CLOCK 'psc%d_mclk' name for clock lookup, only
switch to a fixed string later after device tree based clock lookup
will have become available
to achieve support for MPC512x which is neutral to MPC5200, the
modification was done as follows
- introduce "clock alloc" and "clock release" routines in addition to
the previous "clock enable/disable" routine in the psc_ops struct
- make the clock allocation a part of the port request (resource
allocation), and make clock release a part of the port release, such
that essential resources get allocated early
- just enable/disable the clock from within the .clock() callback
without any allocation or preparation as the former implementation
did, since this routine is called from within the startup and shutdown
callbacks
- all of the above remains a NOP for the MPC5200 platform (no callbacks
are provided on that platform)
- implementation note: the clock gets enabled upon allocation already
just in case the clock is not only required for bitrate generation but
for register access as well
Signed-off-by: Gerhard Sittig
---
drivers/tty/serial/mpc52xx_uart.c | 98 ++---
1 file changed, 81 insertions(+), 17 deletions(-)
diff --git a/drivers/tty/serial/mpc52xx_uart.c
b/drivers/tty/serial/mpc52xx_uart.c
index e1280a2..5be1df3 100644
--- a/drivers/tty/serial/mpc52xx_uart.c
+++ b/drivers/tty/serial/mpc52xx_uart.c
@@ -107,6 +107,8 @@ struct psc_ops {
unsigned int(*set_baudrate)(struct uart_port *port,
struct ktermios *new,
struct ktermios *old);
+ int (*clock_alloc)(struct uart_port *port);
+ void(*clock_relse)(struct uart_port *port);
int (*clock)(struct uart_port *port, int enable);
int (*fifoc_init)(void);
void(*fifoc_uninit)(void);
@@ -616,31 +618,73 @@ static irqreturn_t mpc512x_psc_handle_irq(struct
uart_port *port)
return IRQ_NONE;
}
-static int mpc512x_psc_clock(struct uart_port *port, int enable)
+static struct clk *psc_mclk_clk[MPC52xx_PSC_MAXNUM];
+
+/* called from within the .request_port() callback (allocation) */
+static int mpc512x_psc_alloc_clock(struct uart_port *port)
{
- struct clk *psc_clk;
int psc_num;
- char clk_name[10];
+ char clk_name[16];
+ struct clk *clk;
+ int err;
+
+ psc_num = (port->mapbase & 0xf00) >> 8;
+ snprintf(clk_name, sizeof(clk_name), "psc%d_mclk", psc_num);
+ clk = devm_clk_get(port->dev, clk_name);
+ if (IS_ERR(clk)) {
+ dev_err(port->dev, "Failed to get MCLK!\n");
+ return PTR_ERR(clk);
+ }
+ err = clk_prepare_enable(clk);
+ if (err) {
+ dev_err(port->dev, "Failed to enable MCLK!\n");
+ return err;
+ }
+ psc_mclk_clk[psc_num] = clk;
+ return 0;
+}
+
+/* called from within the .release_port() callback (release) */
+static void mpc512x_psc_relse_clock(struct uart_port *port)
+{
+ int psc_num;
+ struct clk *clk;
+
+ psc_num = (port->mapbase & 0xf00) >> 8;
+ clk = psc_mclk_clk[psc_num];
+ if (clk) {
+ clk_disable_unprepare(clk);
+ psc_mclk_clk[psc_num] = NULL;
+ }
+}
+
+/* implementation of the .clock() callback (enable/disable) */
+static int mpc512x_psc_endis_clock(struct uart_port *port, int enable)
+{
+ int psc_num;
+ struct clk *psc_clk;
+ int ret;
if (uart_console(port))
return 0;
psc_num = (port->mapbase & 0xf00) >> 8;
- snprintf(clk_name, sizeof(clk_name), "psc%d_mclk", psc_num);
- psc_clk = clk_get(port->dev, clk_name);
- if (IS_ERR(psc_clk)) {
+ psc_clk = psc_mclk_clk[psc_num];
+ if (!psc_clk) {
dev_err(port->dev, "Failed to get PSC clock entry!\n");
return -ENODEV;
}
- dev_dbg(port->dev, "%s %sable\n", clk_name, enable ? "en" : "dis");
-
- if (enable)
- clk_enable(psc_clk);
- else
+ dev_dbg(port->dev, "mclk %sable\n", enable ? "en" : "dis");
+ if (enable) {
+ ret = clk_enable(psc_clk);
+ if (ret)
+ dev_err(port->dev, "Failed to enable MCLK!\n");
+ return ret;
+ } else {
clk_disable(psc_clk);
-
- return 0;
+ return 0;
+ }
}
static void mpc512x_psc_get_irq(struct uart_port *por
