[PATCH net-next v3 3/3] net: phy: mscc-miim: add support to set MDIO bus frequency

Michael Walle
2022-04-05T14:02:41Z

Until now, the MDIO bus will have the hardware default bus frequency.
Read the desired frequency of the bus from the device tree and configure
it.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
drivers/net/mdio/mdio-mscc-miim.c | 58 +++++++++++++++++++++++++++++--
1 file changed, 56 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mdio/mdio-mscc-miim.c b/drivers/net/mdio/mdio-mscc-miim.c
index c9efcfa2a1ce..7fd979f68dc0 100644
--- a/drivers/net/mdio/mdio-mscc-miim.c
+++ b/drivers/net/mdio/mdio-mscc-miim.c
@@ -7,6 +7,7 @@
*/

#include <linux/bitops.h>
+#include <linux/clk.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
@@ -30,6 +31,8 @@
#define MSCC_MIIM_CMD_VLD BIT(31)
#define MSCC_MIIM_REG_DATA 0xC
#define MSCC_MIIM_DATA_ERROR (BIT(16) | BIT(17))
+#define MSCC_MIIM_REG_CFG 0x10
+#define MSCC_MIIM_CFG_PRESCALE_MASK GENMASK(7, 0)

#define MSCC_PHY_REG_PHY_CFG 0x0
#define PHY_CFG_PHY_ENA (BIT(0) | BIT(1) | BIT(2) | BIT(3))
@@ -50,6 +53,8 @@ struct mscc_miim_dev {
int mii_status_offset;
struct regmap *phy_regs;
const struct mscc_miim_info *info;
+ struct clk *clk;
+ u32 bus_freq;
};

/* When high resolution timers aren't built-in: we can't use usleep_range() as
@@ -242,9 +247,32 @@ int mscc_miim_setup(struct device *dev, struct mii_bus **pbus, const char *name,
}
EXPORT_SYMBOL(mscc_miim_setup);

+static int mscc_miim_clk_set(struct mii_bus *bus)
+{
+ struct mscc_miim_dev *miim = bus->priv;
+ unsigned long rate;
+ u32 div;
+
+ /* Keep the current settings */
+ if (!miim->bus_freq)
+ return 0;
+
+ rate = clk_get_rate(miim->clk);
+
+ div = DIV_ROUND_UP(rate, 2 * miim->bus_freq) - 1;
+ if (div == 0 || div & ~MSCC_MIIM_CFG_PRESCALE_MASK) {
+ dev_err(&bus->dev, "Incorrect MDIO clock frequency\n");
+ return -EINVAL;
+ }
+
+ return regmap_update_bits(miim->regs, MSCC_MIIM_REG_CFG,
+ MSCC_MIIM_CFG_PRESCALE_MASK, div);
+}
+
static int mscc_miim_probe(struct platform_device *pdev)
{
struct regmap *mii_regmap, *phy_regmap = NULL;
+ struct device_node *np = pdev->dev.of_node;
void __iomem *regs, *phy_regs;
struct mscc_miim_dev *miim;
struct resource *res;
@@ -295,21 +323,47 @@ static int mscc_miim_probe(struct platform_device *pdev)
if (!miim->info)
return -EINVAL;

- ret = of_mdiobus_register(bus, pdev->dev.of_node);
+ miim->clk = devm_clk_get_optional(&pdev->dev, NULL);
+ if (IS_ERR(miim->clk))
+ return PTR_ERR(miim->clk);
+
+ of_property_read_u32(np, "clock-frequency", &miim->bus_freq);
+
+ if (miim->bus_freq && !miim->clk) {
+ dev_err(&pdev->dev,
+ "cannot use clock-frequency without a clock\n");
+ return -EINVAL;
+ }
+
+ ret = clk_prepare_enable(miim->clk);
+ if (ret)
+ return ret;
+
+ ret = mscc_miim_clk_set(bus);
+ if (ret)
+ goto out_disable_clk;
+
+ ret = of_mdiobus_register(bus, np);
if (ret < 0) {
dev_err(&pdev->dev, "Cannot register MDIO bus (%d)\n", ret);
- return ret;
+ goto out_disable_clk;
}

platform_set_drvdata(pdev, bus);

return 0;
+
+out_disable_clk:
+ clk_disable_unprepare(miim->clk);
+ return ret;
}

static int mscc_miim_remove(struct platform_device *pdev)
{
struct mii_bus *bus = platform_get_drvdata(pdev);
+ struct mscc_miim_dev *miim = bus->priv;

+ clk_disable_unprepare(miim->clk);
mdiobus_unregister(bus);

return 0;
--
2.30.2