Changing Baud rate from 9600 to 115200

Hello..
how can i change the baud rate from 9600 to 115200 for UART transmitter in the following VHDL code ?? where the baud rate is represented by:

constant bit_time: STD_LOGIC_VECTOR (11 downto 0) := X"A28";

& I can't really get the relation between the 9600 & A28 which is 2600

entity uart_tx is
Port ( clk : in STD_LOGIC;
clr : in STD_LOGIC;
tx_data : in STD_LOGIC_VECTOR (7 downto 0);
ready : in STD_LOGIC;
tdre : out STD_LOGIC;
TxD : out STD_LOGIC);
end uart_tx;
architecture uart_tx of uart_tx is
type state_type is (mark, start, delay, shift, stop);
signal state: state_type;
signal txbuff: STD_LOGIC_VECTOR (7 downto 0);
signal baud_count: STD_LOGIC_VECTOR (11 downto 0);
signal bit_count: STD_LOGIC_VECTOR (3 downto 0);
constant bit_time: STD_LOGIC_VECTOR (11 downto 0) := X"A28"; -- equivalent to 9600 baud
begin
uart2: process(clk, clr, ready)
begin
if clr = '1' then
state <= mark;
txbuff <= "00000000";
baud_count <= X"000";
bit_count <= "0000";
TxD <= '1';
elsif (clk'event and clk = '1') then
case state is
when mark => -- wait for ready
bit_count <= "0000";
tdre <= '1';
if ready = '0' then
state <= mark;
txbuff <= tx_data;
else
baud_count <= X"000";
state <= start; -- go to start
end if;
when start => -- output start bit
baud_count <= X"000";
TxD <= '0';
tdre <= '0';
state <= delay; -- go to delay
when delay => -- wait bit time
tdre <= '0';
if baud_count >= bit_time then
baud_count <= X"000";
if bit_count < 8 then -- if not done
state <= shift; -- go to shift
else -- else
state <= stop; -- go to stop
end if;
else
baud_count <= baud_count + 1;
state <= delay; -- stay in delay
end if;
when shift => -- get next bit
tdre <= '0';
TxD <= txbuff(0);
txbuff(6 downto 0) <= txbuff(7 downto 1);
bit_count <= bit_count + 1;
state <= delay;
when stop => -- stop bit
tdre <='0';
TxD <= '1';
if baud_count >= bit_time then
baud_count <= X"000";
state <= mark;
else
baud_count <= baud_count + 1;
state <= stop;
end if;
end case;
end if;
end process uart2;
end uart_tx;

Plz help me

baud rate := 9600 bps
bit_time := 2600 (0xa28)

i.e. system clock 24.96MHz (= baud rate * bit_time)

for baud rate := 11500 bps
bit_time := 2170 (0x87a)

i.e. bit_time := 24.96MHz / 11500

so put 0x87a in bit_time field.

11500 ≠ 115200